Chapter 15 Tumors of the Head and Neck
Principles of Surgery Companion Handbook
TUMORS OF THE HEAD AND NECK
|Thyroglossal Duct Cysts|
|Branchial Cleft Anomalies|
|Hemangiomas and Vascular Malformations|
|Connective Tissue Neoplasms|
The thyroid gland originates from the pharyngeal floor at the foramen cecum during the fourth week of gestation. It descends in the midline of the neck close to the hyoid bone. The patent diverticulum that results from this descent is called the thyroglossal duct. When all or a portion of this duct persists, thyroglossal duct cysts or sinuses are formed.
These cysts present as midline masses in childhood. Eighty percent occur at or just below the hyoid bone. The level of the cyst is elevated by protrusion of the tongue, demonstrating its embryologic origin from the base of the tongue.
The differential diagnosis for any midline neck mass around the hyoid bone includes lingual thyroid tissue. Rarely, this may be the patient's only active thyroid gland. Therefore, the presence of thyroid tissue in the normal anatomic location must be confirmed by radioisotope scanning before a midline mass is excised.
Resection of thyroglossal duct cysts with the central portion of the hyoid bone is the recommended treatment. The dissection should follow the sinus superiorly to the foramen cecum so that it is excised entirely.
Branchial cleft cysts, sinuses, and cartilaginous remnants result from incomplete fusion of the branchial clefts. When a portion of a cleft persists, epithelium-lined cysts or sinuses with or without a cutaneous opening may develop. Branchial cleft carcinoma occurs rarely when there is a history of a branchial cleft cyst or the subsequent development of epidermoid carcinoma at that site. Branchial cleft cysts also contain lymphoid tissue and may enlarge in response to upper respiratory infections.
The most common type of branchial cleft anomalies are those of the second cleft. These are present at the middle and lower thirds of the sternocleidomastoid muscle and may be managed by simple excision. Excision of these cysts and sinuses is recommended to avoid the complications associated with recurrent infection. The dissection must be meticulous to avoid injury to the hypoglossal, vagus, and lingual nerves and to the carotid vessels.
Congenital vascular lesions must be clearly classified as hemangiomas or vascular malformations in order to assess their prognosis and establish appropriate management plans. Hemangiomas have an increased mitotic activity and as such may be considered true neoplasms. They are typically absent at birth or may be present as a faint vascular blush. During the first several months of life, they undergo a rapid proliferative phase. Most hemangiomas undergo spontaneous involution by the age of 7 years. Systemic dexamethasone therapy for a short course has been found to arrest the growth of large lesions during their proliferative phase. Photodynamic laser therapy may be helpful in preventing the onset of the proliferative phase of hemangiomas.
Vascular malformations, unlike hemangiomas, have a normal rate of endothelial cell turnover. High-flow lesions result from gross abnormalities connecting the arterial and venous systems and may cause catastrophic problems of massive hemorrhage, high-output congestive heart failure, and hemolytic anemia.
Lymphatic malformations (cystic hygromas) classically occur in the neck or floor of the mouth. They normally grow proportionally to the child and do not regress spontaneously. Therefore, the management of such malformations is often surgical. Indications for early surgical resection include recurrent infections, obstructive symptoms, hemorrhage, and significant aesthetic deformities.
The lower lip is subject to chronic irritants such as pipe smoking, lip biting, or actinic exposure. The basal layer of the epidermis develops dysplasia, creating thickening of the superficial mucosa. This thickening or hyperkeratosis becomes clinically visible and palpable. A proliferation and abnormal orientation of epithelial cells, or dyskeratosis, may then follow, ultimately leading to carcinoma in situ. With penetration of the basement membrane, an invasive squamous cell carcinoma develops. When dyskeratosis or carcinoma in situ is present over a large extent of the lip surface, an excision of the entire vermilion border should be considered.
Mucous retention cysts are benign lesions of the oral lining that have no true epithelium. They are caused most often by rupture of the duct system with extravasation of mucus. The most common location of a mucous cyst is the labial mucosa of the lower lip. The treatment of choice is excision. A ranula is a type of mucous retention cyst that arises from the major salivary glands, most commonly the sublingual. This, too, is managed by excision.
An epulis is a granulomatous lesion of the gingiva. It represents an exaggerated inflammatory response to minor injury. Only symptomatic epulides need to be excised.
Peripheral giant cell reparative granulomas also occur commonly on the gingiva. The giant cell of origin appears to resemble an osteoclast. These granulomas are polypoid, submucosal, and fibrous. Radiographic examination may reveal erosion of the underlying bone. Excision must be complete to prevent recurrence.
The tongue and larynx are common locations for the development of papillomas. They are caused by the human papillomavirus, which induces squamous epithelial proliferation. Eradication may be accomplished by excision or cauterization.
Granular cell myoblastoma is a rare benign tumor of the tongue that originally was described as of embryonal muscle cell origin. These tumors are now believed to derive from Schwann cells and have been found to arise throughout the aerodigestive tract. In the tongue these tumors form firm submucosal swellings in the middle third and can mimic squamous cell carcinoma. Wedge excision is recommended.
Ulcers of the oral lining are common. The idiopathic aphthous ulcer is the most common type. The cycle of painful ulceration and spontaneous healing may occur several times a year. Viral infections, nutritional deficiencies, and emotional stress are common etiologic factors. These ulcers often respond to topical steroids.
Lichen planus is a degenerative mucocutaneous disease with a probable autoimmune basis. The oral lesions appear with or without cutaneous manifestations and may, at times, become erosive. Squamous cell carcinoma has been found in association with lichen planus infection. Systemic and topical retinoids are being evaluated in the treatment of this condition.
Polyps are the most common benign tumor of the nasal cavity and paranasal sinuses. They are often multiple, involving both sides of the nasal cavity. Polyps may present with nasal obstruction, mucoid nasal discharge, or anosmia. Those which arise in the region of the turbinates and ethmoid are mainly allergic in origin, whereas those of the posterior nasal cavity are most often infectious. Medical management should include an evaluation for allergies. Also, there is an association with aspirin use in the formation of nasal polyps. Steroid nasal sprays may be helpful. Surgical intervention occasionally may be necessary.
Juvenile nasopharyngeal angiofibromas are benign but highly expansible and destructive fibrovascular neoplasms that typically arise in adolescent males between 10 and 20 years of age. Originating in the superior nasal cavity, they can erode widely into the paranasal sinuses, orbit, pterygomaxillary fossa, and middle cranial fossa. Early symptoms include nasal obstruction and epistaxis, whereas more advanced lesions can produce anosmia, proptosis, or cranial nerve dysfunction. Management commonly requires preliminary angiography followed by surgical extirpation. Approximately 10 percent require a combined intracranial-extracranial approach. Radiation therapy generally is reserved for residual or recurrent disease, although its successful use as a primary modality also has been reported.
Mucous retention cysts arise as a result of blockage of secretions from microscopic secretory ducts. The fluid mass is separate from the bony wall. Radiographically, these cysts appear as masses profiled by air. They most commonly occur in the maxillary sinus and are asymptomatic. Treatment rarely is necessary.
Mucoceles result from macroscopic blockage of a sinus ostium by an epithelial or osseous neoplasm or inflammation or trauma. Computed tomography (CT) or magnetic resonance imaging (MRI) shows the sinus to be filled and the bony wall thinned. Mucoceles occur most commonly in the frontal sinuses and cause frontal headaches. About 60 percent erode through the orbital roof and can cause proptosis, diplopia, and blindness. Treatment is evaluation of the sinus by an open approach. The entire mucosa should be removed and the sinus obliterated.
The most common benign neoplasm of the larynx is the papilloma, accounting for more than 90 percent of such tumors. They arise most commonly on the true vocal cords and, as such, present most often with hoarseness. They may be found in any site within the larynx. They are likely caused by human papillomavirus. In adults, masses are most often solitary and rarely recur after excision. In the juvenile group, the lesions tend to be multiple and may recur and spread rapidly after excision. Laryngeal papillomas today most often are treated with laser obliteration. Other less common benign tumors of the larynx include oncolytic tumors and granular cell myoblastomas. Chondromas of the larynx are rare, benign, cartilaginous neoplasms that usually occur on the cricoid cartilage. They cause hoarseness, respiratory obstruction, or dysphasia. All these benign neoplasms are managed by conservative excision.
Odontogenic tumors are derived from tooth development. Ameloblastoma is a benign tumor that arises from the dental lamina and is often associated with impacted teeth in young patients. The usual presentation is that of a painless mass of the jaw with a multilocular radiolucent radiographic appearance. These tumors occur most frequently in the mandible. Treatment consists of resection of the entire lesion with a margin of bone to prevent local recurrence. Another group of odontogenic tumors includes calcifying odontogenic cysts, ameloblastic fibroma, cementomas, and keratocysts. These are generally less aggressive than ameloblastoma. They are treated effectively by enucleation and excision of the entire lining of the lesion.
This group of tumors arises from bone that is not involved in tooth development. Torus is a benign, slow-growing projection from the surface of a bone. Torus palatinus occurs in the midline of the hard palate, and torus mandibularis usually develops on the lingual surface of the mandible opposite the premolar, often bilaterally. They are both common lesions. Tori often begin around puberty and are slow growing. They can induce ulceration of the overlying mucosa, thereby mimicking a mucosal neoplasm. No therapy is needed unless they interfere with speech, mastication, or the use of dentures. Exostoses are similar to tori and also commonly occur in the jaws. These are localized overgrowths of bone that may be nodular, pedunculated, or flat and often are multiple. Only symptomatic masses require excision. Osteomas are slow-growing tumors of mature bone that arise within the periphery of the involved bone. They arise most commonly on the mandible, on the lingual aspect of the ramus, or on the lower border of the angle of the mandible. Excision is advised when continued growth encroaches on vital structures or becomes cosmetically unacceptable. Multiple osteomas are one of the manifestations of Gardner syndrome, with the others being multiple inclusion cysts of the skin, supernumerary teeth, and familial polyposis.
General Considerations Invasive carcinomas of the head and neck disrupt normal function of alimentation and respiration. The derangements of feeding, breathing, and speaking may present as malnutrition, upper airway obstruction, and recurrent aspiration pneumonia. As many as 60 percent of patients dying with head and neck malignancy expire without clinical evidence of metastasis beyond the local-regional disease. Central nervous system invasion, rupture of the great vessels, airway obstruction, and invasive local obstruction are common causes of death in these patients. Because of the predominant local and locoregional natural history of this disease, significant attention must be paid to local diagnosis and therapy. Most malignant tumors that develop in the head and neck are squamous cell carcinomas (epidermoid carcinomas) originating from the respiratory and stratified squamous epithelium of the upper aerodigestive tract. Most squamous cell carcinomas of the head and neck behave similarly. Their unique clinical expression depends on the interruption of normal activity inherent in their epicenter and those areas to which they spread. Nasopharyngeal carcinoma may present with nasal stuffiness and progression to cranial nerve dysfunction. Carcinoma of the floor of the mouth may present with pain. Tethering of the tongue and dysphagia result in malnutrition and possible aspiration. Survival of the patient with head and neck cancer requires consideration of both tumor growth and residual local function in formulation of a plan for therapy. The appropriate selection of radiation therapy, extirpative surgery, chemotherapy, and reconstructive surgery is crucial in the attempt to prolong the patient's life and restore reasonable function and appearance. A multidisciplinary approach to this group of tumors is essential.
Epidemiology There are between 30,000 and 40,000 new cases of head and neck cancer and 10,00015,000 deaths attributed to this disease each year. Approximately one-third of patients who develop a squamous cell carcinoma of the upper aerodigestive tract will die of it. In the United States, there seems to be a clear-cut relationship between squamous carcinoma and the chronic use of tobacco and alcohol together. The use of either tobacco or alcohol alone increases the likelihood of squamous cell carcinoma, but the combined use of these drugs increases the risk greatly. Despite the differences in proposed causative agents of head and neck cancer throughout the world, it appears clear that an important factor in the origin of squamous cell carcinoma is a chemical carcinogen and that a linear dose-time risk ratio is likely. Therefore, prevention should be possible. The role of viral carcinogenesis via initiation or promotion is unclear but certainly suspicious. Patients with papillomatosis caused by human papillomavirus of the nasal cavity and larynx have been observed to be at higher risk for the development of squamous cell carcinoma. Elevated antibody to Epstein-Barr virus (EBV) is associated with the presence of nasopharyngeal carcinoma but is not specific enough to be of clinical use because viral infection is so common. That the virus plays either an initiating or promoting role in carcinogenesis is suggested not only by the presence of the EBV genome in cervical metastases, as well as by the primary tumor arising in the nasopharynx, but also by its absence in the lymph nodes of EBV antibodyseropositive patients who did not contain tumor and its absence in metastatic tumors of other histology. Squamous cell carcinoma of the upper aerodigestive tract appears to be disproportionately common and unusually aggressive in patients with acquired immune-deficiency syndrome (AIDS), as it is in other immune-deficient states such as chronic lymphocytic leukemia. Oral and pharyngeal presentations of Kaposi's sarcoma are common in human immunodeficiency virus (HIV)positive patients and may require surgical or radiotherapeutic intervention.
Natural History Viral infection, chronic irritation by ill-fitting dentures, trauma, or infection from poor dental hygiene may elicit a response from the epithelium known as hyperplasia or papillomatosis, wherein cells with normal DNA configuration and organelle structure proliferate, resulting in more prominent intraluminal projection of the mucosa deep into the submucosa. Most of the clinical changes that reflect these histologic alterations include hyperplasia and hyperkeratosis. These changes have been grouped under the term leukoplakia (white patch). More recent evidence suggests that leukoplakia is not in itself premalignant but simply a manifestation of chronic irritation. Cellular manifestations of malignancy result in the diagnosis of epithelial dysplasia. Lack of a normal cellular progression to maturation characterizes dysplastic epithelium. Nuclei are larger and hyperchromatic and show mitotic activity. Cell layers become disorganized with loss of the gradual ascent to the epithelial surface and presence of immature cells at the basement membrane as well as the epithelial surface. The change from hyperplasia is thought to be irreversible and the initial step in ultimate carcinogenesis. The clinical manifestation of these histologic changes has been termed erythroplasia or erythroplakia, or red patch. These lesions appear reddish, are frequently exudative, and may have associated leukoplakia. Biopsy or excision is mandatory because they are premalignant and also may indicate the presence of another adjacent malignancy.
The virulence of the primary tumor and its likelihood of metastasis or ability to cause the demise of the host have been estimated by a number of methods. Size of the primary tumor is the main parameter determining its clinical stage in the TNM staging system adopted by the American Joint Committee on Cancer (AJCC) and other worldwide organizations. Although a crude method, it is fairly reliable in suggesting the prognosis of the patient and the appropriate form of therapy. Histologic characteristics such as degree of differentiation, pattern of invasion, microvascular invasion, and perineural invasion and tumor thickness have been used to predict the likelihood of lymph node metastasis and overall prognosis. Other microbiologic techniques that help to predict prognosis include aneuploidy, thymidine labeling index, expression of histocompatibility antigens, and levels of epithelial growth factor receptor. The histologic, biochemical, and genetic characteristics of head and neck tumors also have been used in an attempt to predict response to radiation therapy and chemotherapy.
As with most solid tumors, the most cogent prognosticator of head and neck cancer is the presence or absence of lymph node metastases. Clinical and pathologic staging of the neck according to the AJCC system depends on the number of lymph nodes, size of the lymph nodes and fixation to the skin or subjacent neck muscles, and laterality with respect to the primary tumor. Although there are certainly many determinants of primary tumor behavior, size and differentiation are useful predictors of risk of metastasis. Increasing T stage is generally reflective of increasing N stage. Distant metastasis, however, is more closely related to N-stage than to T-stage disease. In a study of Stage III carcinoma of the oral cavity, the 2-year survival of patients with no lymph node metastases was 87 percent; with intracapsular lymph node metastases, 75 percent; and with cervical metastases with extracapsular spread, only 39 percent. Uncontrolled growth of squamous cell carcinoma of the neck results in carotid artery hemorrhage; invasion of the sympathetic ganglia resulting in Horner syndrome; erosion of the cervical vertebrae; invasion of cranial nerves IX, X, XI, and XII at the base of the skull; airway obstruction; and brachial plexus palsy. The site of the primary tumor also dictates the site of cervical metastases. Cancers of the tonsils and the base of the tongue have higher rates of metastasis to the neck, whereas buccal mucosa and palate lesions have low rates of metastasis. The presence of distant metastases from squamous cell carcinoma ranges from 31 percent of patients with no evidence of cervical metastases to 59 percent of those with extensive neck disease. Despite this relatively high incidence, they are not uniformly the cause of death. Although metastasis to any site is possible, the lung, bone, skin, and liver are the most common sites. Systemic effects of both local and systemic disseminated tumors include hypercalcemia from bone metastases and elaboration of parathormone-like peptides, as well as the syndrome of inappropriate diuretic hormone (SIADH) from vasopressin-like substances. There is some evidence that the widespread use of chemotherapy has changed the natural history of metastatic squamous cell carcinoma, increasing the frequency of patients dying with disseminated disease (Fig. 15-1).
FIGURE 15-1 Malignant processes in the head and neck.
Diagnosis and Evaulation Important considerations of the history and physical examination for patients with potential head and neck cancer include a history of chronic tobacco and alcohol abuse. Men over age 40 with such a history comprise 80 percent of patients with head and neck cancer. In addition, a previous occurrence of lung cancer, esophageal cancer, or other head and neck malignancy places patients in a higher-risk category. Immunodeficiency states such as occur with transplant therapy for renal failure, malnutrition, and AIDS are also significant.
Physical findings relate to late tumor stage presentation, which is common. Pain in the ear of an adult is a relatively rare problem and usually indicates a malignancy of the oral cavity, oropharynx, or larynx. Formication, the feeling of ants crawling along the lip or cheek, may represent infraorbital nerve invasion by carcinoma. A change in speech is another physical indicator of oral carcinoma. Hoarseness is a sign of vocal cord impairment by local tumor growth. Airway compromise is usually a late symptom but can precipitate an emergency. Evaluation of the patient includes visualization of the entire upper aerodigestive tract. Careful intraoral examination and indirect mirror laryngoscopy are essential. A flexible nasopharyngoscope has added greatly to complete examination. Mobility of the tongue always should be noted. Position and movement of the vocal cords are also important. Limited motion of the mandible may come from direct tumor invasion or from invasion of tumor through the retromolar trigone. This may cause the uncomfortable symptom of trismus, an ominous clinical sign. Examination of the neck will reveal the presence or absence of metastatic lymph nodes. Careful examination will allow the examiner to assign an N stage to the patient, which is an important prognostic feature. A careful neurologic examination is also important to reveal evidence of more extensive disease. These findings would include extraocular movement disorders or Horner syndrome from invasion of cervical sympathetic nerves. Distant metastases are evaluated by laboratory procedures and radiologic examination, as well as by history and physical examination. Pleuritic pain or shortness of breath may indicate lung involvement, and distinct pain at specific sites may indicate bone involvement.
Definitive diagnosis depends on a biopsy. If the primary site is visible, a wedge biopsy should be taken at the edge of the tumor. Because of the significant incidence of synchronous primaries, however, evaluation of the entire upper aerodigestive tract is useful. Triple endoscopy, i.e., bronchoscopy, esophagoscopy, and direct laryngoscopy, is advisable for ideal workup of head and neck cancer. Radiologic evaluation of head and neck disease usually involves assessment of the mandible with dental films, mandibular series, and panoramic films. Bone scans frequently are falsely positive; rather, CT scanning is a very sensitive method of diagnosing bone invasion. MRI is probably the most accurate and useful method of evaluating the mandible as well as other areas of head and neck.
Therapy Clinical therapy or palliative therapy for a given patient is based on the clinical stage (TNM) of the tumor at the time of presentation. Curative treatment methods are oriented toward total extirpation of locoregional disease. Palliative procedures are designed to produce relief of pain or airway obstruction or improvement in local function and hygiene. Palliative procedures are occasionally justifiable in the presence of distant metastases. Subtotal resection of local or locoregional disease is unlikely to be of benefit in any situation. For small tumors (<2 cm), surgery and radiation therapy, well-planned and appropriately executed, will have equivalent local control and survival rates. The choice then depends on patient compliance, volition, associated disease, expense, interference with normal function, and available facilities. As the size of the tumor increases to T2 or greater, the likelihood of local control and ultimate cure with radiation therapy alone decreases. Therefore, surgery, or surgery with adjuvant radiation therapy, becomes preferable with larger lesions. The use of chemotherapy in a postoperative setting has been unsuccessful in most trials. Despite high response rates to preoperative administration of cis-plantinum and 5-fluorouracil (5-FU), there has not been a survival advantage with this novel form of treatment.
The basic principle of solid tumor therapy is en bloc treatment, either resection or radiation therapy of the primary tumor and the regional disease in the neck. When palpable lymph nodes are present in the neck, confirmation of metastatic disease may be obtained with fine-needle aspiration (FNA) and cytology, or the decision to proceed with therapy may be made on purely clincial grounds. Palpable or radiologically positive lymph node metastases require surgical therapy in the form of some type of neck dissection usually performed in continuity with resection of the primary tumor. Subclinical disease or micrometastases may be treated by a modification of neck dissection or radiation therapy depending on the modality chosen for treatment of the primary site.
Reconstruction Improved methods of reconstruction, better pathologic analysis at surgery, and a more comprehensive understanding of the natural history of head and neck cancer have made single-stage reconstruction at the time of the initial surgical therapy the present standard of care in most patients. Resection of the primary disease and regional metastatic disease, confirmation of disease clearance by frozen section of the margin, and immediate reconstruction are usually possible for squamous cell carcinoma of the upper aerodigestive tract. In malignancies where frozen-section analysis may be inaccurate when bone is involved, in recurrent disease with previous radiation therapy, or when there is uncertainty about other aspects of the resection, secondary reconstruction may be more appropriate.
The basic needs presented by surgical resection are restoration of continuity of the alimentary tube with epithelial lining, provision of reliable external coverage for protection of the great vessels and bony structures, and separation of the central nervous system and upper aerodigestive tract. The fundamental improvements in reconstruction over the past decades have been the ability to transfer large volumes of well-vascularized tissue to the head and neck area. The realization came in the 1970s that the blood supply to the skin came not only from the randomly oriented subdermal plexus vessels and axial cutaneous vessels but also from perforating vessels from adjacent muscle. Large, flat muscles of the thorax can be rotated on their long vascular pedicles. This concept transformed reconstruction, in particular that of head and neck defects. The pectoralis major, latissimus dorsi, trapezius, sternocleidomastoid, and platysma muscles are all useful, either alone or with their overlying skin. Microvascular reconstruction or free-tissue transfer has made it possible for the surgeon to close any defect in the head and neck, no matter how large or complex. The large number of methods available allows the reconstructive surgeon to choose the method or methods most suitable to a specific site and analyze the results.
Complications Complications of treating head and neck cancers can be categorized as anatomic, physiologic, technical, or functional. The best approach to complications is prevention. Early restoration of positive nitrogen balance, good preoperative pulmonary hygiene, controlled diabetes mellitus, and weaning from alcohol dependence are important nonspecific measures. Use of preoperative antibiotics decreases the likelihood of wound infection and its sequelae. Preoperative radiation therapy given in therapeutic doses definitely increases the risk of complications. Patient education is crucial to ensure cooperation in what may be a difficult postoperative rehabilitation.
Nerve injury is a frequent complication of head and neck cancer surgery. Injuries due to traction, electrocautery, or other technical misadventures may occur. Careful technique and good knowledge of the normal anatomy are critical. Ischemia of tissues in the wound is another cause of complications. Preoperative irradiation interferes with good blood supply to tissues. Hypoparathyroidism is another complication that can occur secondary to radical laryngopharyngectomy. Obstruction of one or both of the jugular veins, when combined with lymphedema of the face, may cause intracerebral edema. The breakdown of the skin wound or necrosis of a transferred flap may result in exposure of a previously irradiated carotid artery. Bacterial infection and subsequent rupture are not uncommon in this situation and must be treated as a surgical emergency. Other catastrophic complications that can occur are acute airway obstruction from a hematoma or a dislodged tracheostomy tube, tracheoinnominate fistulas, and massive hemorrhage. Pharyngocutaneous fistulas also may occur and must be treated by transfer of a musculocutaneous flap for provision of well-vascularized tissue.
Carcinoma of the lip is much more common in men than in women. The lower lip is by far the most common site, with squamous cell carcinoma as the most common histology. Pipe smoking and chronic thermal injury have been known for years to be the carcinogenic stimulus. Exposure of the protuberant lower lip to high doses of ultraviolet radiation in sunlight also results in malignancy.
Most lesions are well-differentiated Stage I carcinomas. Nodal metastases usually occur to the submental or submandibular nodes but are present in only 1015 percent of patients. Standard treatment is local excision or radiation, with cure rates for either of approximately 90 percent.
Surgical therapy requires resection of the disease with a clear margin of normal tissue. If lymph nodes are palpable, ipsilateral or bilateral neck dissection is indicated. Reconstruction can be performed with the opposite lip used as a donor site.
The oral cavity includes the buccal mucosa, gums, retromolar trigone, floor of the mouth, and hard palate. Carcinogenesis in the oral cavity and the natural history of subsequent disease are generally similar independent of these anatomic areas.
The buccal mucosa extends from the commissures of the lips to the pterygomandibular raphe and from the maxillary to the mandibular alveolus on both sides. Cancer of the buccal mucosa makes up about 5 percent of all oral cancers, and as in other sites, there is a significant male predonminance. Most cases are advanced at the time of presentation, with a high incidence of nodal metastasis.
Verrucous carcinoma is a subset of buccal mucosa lesions that presents as an exophytic mass with a cellular histology characteristic of malignancy but lacking invasive aspects. This lesion is more common in females and may be related to papillomavirus. Forty percent of these patients may have other sites of invasive carcinoma in the oral cavity.
Infiltrative carcinoma of the buccal mucosa occurs commonly in tobacco chewers and snuff dippers in the United States. Standard therapy is surgical resection with or without adjuvant radiation therapy. Survival rates range from 6075 percent for localized disease and from 2545 percent for local-regional disease. Reconstruction of large buccal mucosa defects usually has included the combined use of the pectoralis major flap for internal lining and the deltopectoral skin flap for skin coverage.
The hard palate is not a common site of intraoral carcinoma. When neoplasia occurs here, it is usually benign or a malignant tumor of the minor salivary glands. Treatment is surgical resection with or without adjuvant radiation therapy. Because of the underlying bone, definitive radiation therapy is rarely useful. Cervical metastases are rare. The resulting defects are best treated with a dental prosthesis. Massive defects may require temporalis muscle flap.
FLOOR OF THE MOUTH
The floor of the mouth is a horseshoe-shaped area between the tongue and lingual surface of the mandible. The papillae that allow Wharton's ducts to empty into the oral cavity lie at the anterior border of this area. Fifteen percent of oral cancers arise in this area. Direct extension of tumor into the neck and bilateral cervical metastases are frequent. Medial growth of the primary tumor tends to invade the ventral surface of the tongue, whereas lateral growth invades the mandible. Most patients present with advanced disease.
Resection of floor of the mouth cancers with an adequate margin of normal tissue frequently requires removal of a segment of mandible. Therapeutic doses of radiation may result in ischemic necrosis of the mandible, which is difficult to treat. Surgical resection combined with modest doses of adjuvant radiation is appropriate for advanced disease. Survival rates are 7080 percent for Stage I disease and 3545 percent for Stage III disease. In reconstruction, a radial forearm free flap provides an excellent lining of this area that can drape over the mandible and allow free movement of the tongue while providing a watertight seal. The choice of reconstruction depends on the amount of mandible to be removed.
Cancer of the oral tongue is second only to the lip as the most common primary site. Again, tobacco and alcohol are the most common associated conditions. Immunosuppressed patients of any age, however, may be at higher risk for tongue cancer.
The tongue is a complex muscular structure receiving motor intervention from the hypoglossal nerve. The tongue is connected to the hyoid bone by the hypoglossus muscle and superiorly to the mandible by the genioglossus muscle. The ventral surface of the tongue has openings of the sublingual ducts. On the dorsal surface are papillae with specialized sensory organs for taste.
Malignancy of the tongue occurs most frequently at the midportion of the lateral tongue and is often asymptomatic. Radial spread through the tongue may extend submucosally to the base of the tongue and across the midline or laterally to the floor of the mouth. Ipsilateral metastases are common to the submandibular and submental nodes. Clinical evidence of cervical mestastasis is present in 4060 percent of patients. Survival rates are 7090 percent for localized disease and 3040 percent for regional metastases.
Definitive therapy for carcinoma of the tongue can be attempted with both external-beam radiation or interstitial radiation. External radiation in doses of 6500 cGy may be useful, but implantation of afterloading devices can deliver doses in the range of 10,00015,000 cGy over a small area with greater effect.
The surgical therapy of carcinoma of the tongue consists of resection of the tumor with a margin of normal tissue and en bloc removal of the regional lymph nodes. Most surgeons are uneasy about the ability to obtain clear margins with such resections, which has led to common use of adjuvant radiation therapy. Resection at the base of the tongue may predispose the patient to aspiration and ultimate respiratory failure. Despite these problems, total glossectomy with or without laryngectomy has been shown to be a valuable procedure for both cure and palliation. A 3-year survival of 53 percent has been achieved in one series, with 80 percent of patients demonstrating intelligible speech if the larynx is preserved and 93 percent regaining the ability to maintain their nutritional status by oral alimentation.
There is no satisfactory way to reconstruct the tongue. Denervation of the tongue by resection or injury to both hypoglossal nerves usually renders the patient incapable of swallowing or effective speech. After surgical resection of a portion of the tongue, the reconstructive goal is to allow free mobility of the remaining tongue while providing a watertight seal to the oral cavity. Advancing the posterior mobile tongue or setting back the excess anterior tongue may provide the optimal solution. The defect of total glossectomy involves the tongue, floor of the mouth, and sometimes the pharyngeal and laryngeal mucosa. Restoration of oral continence usually requires significant soft tissue. The pectoralis major flap serves well to replace the entire floor of the mouth, as does the jejunal free flap, which also can replace the pharynx and crevice esophagus. When a portion of the mandible must be resected for carcinoma of the oral tongue, the urgency of reconstruction depends on what part of the mandible has been resected. Resection of the symphysis or anterior segment of the mandible is a devastating problem that requires immediate reconstruction. Vascularized bone from the scapula, fibula, iliac crest, radius, or metatarsal is an excellent method of reconstruction. Other areas of the mandible are less demanding of reconstruction.
The pharynx is the continuation of the muscular tube that constitutes the alimentary tract. It is divided into three sections, each with a slightly different function: the nasopharynx, the oropharynx, and the hypopharynx. An important characteristic of the pharynx is its role in separating the respiratory and alimentary tracts, and its specialized structures reflect this function.
The oropharynx contains the base of the tongue from the circumvallate papillae back, the tonsils, the oral soft palate, the lateral pharyngeal walls, and the posterior pharyngeal wall. The boundaries of the hypopharynx are reflections of the anatomy of the larynx. The pharyngeal wall runs from the tip of the epiglottis to the inferior border of the cricoid cartilage. The anterior border of the hypopharynx is the postcricoid mucosa, and the lateral surfaces are the mucosal cavities on both sides of the larynx known as the piriform sinuses.
Carcinoma arising from the circumvallate papillae in the base of the tongue frequently remains asymptomatic and undiagnosed until late-stage disease is present. The disease is commonly overlooked because of reluctance of primary care physicians to perform indirect laryngoscopy or palpate the base of the tongue. The central location of these lesions gives rise to cervical lymphatic metastases in up to 70 percent of patients. In addition to epidermoid carcinoma, minor salivary lesion gland tumors are also seen. Exophytic lesions with cells resembling lymphocytes arise in the tissues of Waldeyer's ring, the tonsils, the lingual palatine, and the base of the tongue. These lymphoepitheliomas behave like nasopharyngeal carcinoma and have been characterized as undifferentiated carcinomas with lymphocytic infiltration. Such lesions, both at primary lesions and at cervical metastases, are more radiosensitive than the garden variety infiltrative keratin-producing squamous cell carcinoma. Two-year local control rates are 75 percent for T1 lesions. Because of the proximity to and functional relationship of the base of the tongue to the larynx, interference with laryngeal elevation and closure of the epiglottis with the attendant aspiration pneumonitis is a hallmark of carcinoma of the base of the tongue.
Advanced disease at the primary site or disease with cervical metastases requires surgical therapy. If the lesion is lateral enough, partial glossectomy may be adequate. However, since resection of the base of the tongue usually removes the hypoglossal nerve to the tongue, subtotal or posterior glossectomy is unlikely to leave functional tissue. Radical resection may require total glossectomy with or without laryngectomy. Combined use of surgery with postoperative adjuvant radiation therapy results in 5-year survival of 5060 percent for Stage III disease.
Reconstruction of defects arising from resection at the base of the tongue should attempt to close the pharynx and oral cavity with tissue that will heal to previously irradiated mucosa or withstand subsequent irradiation and still not interfere with the function of tissues left intact by the curative resection. The provision of sensate tissue to the area surrounding the larynx to prevent aspiration is also an important consideration. Occasionally, local tissue can be mobilized for closure without tension to avoid a fistula and provide sensate mucosa.
Squamous cell carcinoma may arise in the tonsil or the tonsillar pillars. As one of the Waldeyer's ring structures, the tonsil shows a higher incidence of lymphoepithelioma than other sites. Individuals with tumors of the tonsil present predominantly with late-stage disease. Cervical metastases at the time of presentation were seen in up to 67 percent of patients. Determination of the extent of local disease in advanced tumors is of considerable importance in decision making and execution of therapy. The site of local extension is particularly important because in treating patients with radiation therapy, geographic misses secondary to underestimation of local extent are a common reason for failure.
Carcinoma of the tonsil appears to be more radiosensitive than other primary-site squamous cell carcinomas. The usual approach to disease orginating at this site is to treat for curative intent with radiation in doses ranging from 55007000 cGy to the primary site and bilateral cervical lymph node drainage areas. If there is bulky neck disease or extension of the primary tumor into adjacent bone or pterygoid muscles, surgical resection, reconstruction, and postoperative radiation therapy are safe and more effective.
The challenge of reconstruction in tonsillar carcinomas is a function of the dimensions of local growth and history of previous radiation. The soft tissue defect in the lateral wall of the pharynx created by a superficial lesion can be resurfaced easily with a skin graft, deltopectoral flap, or fasciocutaneous free flap. More extensive lesions may require transposing a pectoralis major musculocutaneous flap into the lateral pharynx.
Isolated carcinoma of the soft palate is rare; the disease usually occurs in combination with other frank malignancies or premalignant entities such as erythroplakia. The oral side of the soft palate is by far the most common site for malignancy. Ipsilateral cervical lymph node metastases to the jugulodigastric nodes occur in 50 percent of patients, with bilateral metastases seen in 15 percent of patients.
Treatment of soft palate carcinoma follows the usual principle that small lesions are effectively eradicated by radiation therapy of approximately 6500 cGy and that combined therapy, i.e., surgery with adjuvant radiation therapy, is necessary for best results in larger tumors. The use of radiation therapy is particularly important because of the difficulty of reconstructing the soft palate after surgery.
Thy hypopharynx consists of the piriform sinuses, the lateral and posterior mucosal borders of the larynx, and the posterior pharynx. Tumor growth in this area is intimately related to the function of the larynx. Rather than size, the T stage of a piriform sinus lesion increases with extent into the medial wall or fixation of the vocal cord. Another consideration in hypopharyngeal carcinoma is the extent of disease in the cervical esophagus. Such advanced-stage local disease is common, with only 1015 percent of cases confined to only one site in the hypopharynx. Even in small lesions there is a high likelihood of lymph node metastases. Between 50 and 60 percent of patients present with palpable lymphoadenopathy, and 40 percent of patients with clinically negative nodes demonstrate metastatic disease after elective neck dissection. Distant metastases at presentation and with treatment of disease appear to be more common than at other primary sites.
Since it is unusual for hypopharyngeal lesions to present at early stage, the treatment is usually combined, consisting of surgery followed by adjuvant radiation therapy. The extent of the surgery depends on the proximity to the larynx. Laryngopharyngectomy with bilateral modified neck dissection is the procedure that is most frequently necessary. With such an approach, survival rates of 2040 percent have been achieved.
Primary closure of the pharyngeal mucosa after partial laryngopharyngectomy results in a high likelihood of fistula. A free autograft of bowel or skin is the preferred method for reconstruction. When a circumferential defect is present, the problem of bulk and gravity can be circumvented somewhat by skin grafting the prevertebral fascia as the posterior wall of the new pharynx and using the pectoralis major muscle and its overlying skin as a 270-degree reconstruction to complete the pharyngeal conduit.
When total esophagectomy is part of the treatment for carcinoma of the pharynx, transposition of the stomach or colon through the thorax can reconstitute the alimentary canal. Gastric pull-up with the stomach based on the right gastric and gastroepiploic vessels is a fairly reliable technique but has a mortality rate of 1020 percent. Although colon, segments of stomach, and jejunum have all been used, the greatest experience has been with the jejunal free autograft. Successful reconstruction using the jejunum has been achieved in 90 percent of patients approached with this method. Eighty percent of the total group will achieve total per oral alimentation.
Squamous cell carcinoma of the cervical esophagus presents the same reconstructive demands as that of the hypopharynx. The mode of spread of the local disease, however, may involve submucosal skip areas and thus require total esophogectomy. The lymphatic drainage of the cervical esophagus is oriented more toward the mediastinum and parapharyngeal nodes than laterally into the neck and requires a different approach for lymphadenectomy.
Carcinoma of the nasopharynx makes up 0.25 percent of new cancers in the United States. It is, however, endemic in Southeast Asia, particularly in southern Chinese populations. The incidence is much lower in Orientals who have emigrated to North America.
The nasopharynx is a small, mucosal-lined, boxlike cavity at the base of the skull containing the pharyngeal tonsil and the openings of the eustachian tubes and the sphenoid sinus. Lesions may obstruct the eustachian orifices on the choanae, leading to hearing loss, nasal stuffiness, or obstruction and epistaxis. Infiltration and bony erosion of the base of the skull into the cavernous sinus result in cranial nerve palsies, the most common being that of the abducens nerve, followed by the trigeminal nerve and the other oculomotor nerves. The most common presenting sign of nasopharyngeal carcinoma is a mass in the neck secondary to cervical metastasis.
CT scanning has helped delineate invasion of both paranasopharyngeal fascial planes and bony skull invasion in the absence of cranial nerve palsy. Prognosis depends on the histology. Keratinizing squamous cell carcinoma has the worst 5-year survival. Round cell carcinomas and mixed nonkeratinizing carcinomas are much less virulent.
Therapy with radiation in doses varying from 50008400 cGy to the primary site with 50007000 cGy to both sides of the neck results in a 5-year survival rate varying from 100 percent for Stage I disease to 30 percent for Stage IV disease. The total dose of radiation has an effect on survival, with those patients receiving lower total doses having a poorer survival. Sixty-two percent of cranial nerve defects can be reversed by radiation therapy, with an overall 30 percent survival in this subset of patients. Distant metastatic disease in nasopharyngeal carcinoma is common, particularly in patients who have bulky cervical metastases. Currently, however, adjuvant chemotherapy has not been particularly successful in improving survival.
The nasal cavity and paranasal sinuses are exposed to many carcinogens in the air, and yet malignacies in these sites are rare. Nasal cavity carcinoma is endemic in areas of South Africa where inspired snuff has a high concentration of nickel. There also may be an increased risk of adenocarcinoma of the paranasal sinuses in woodworkers secondary to inspired wood dust. Squamous cell carcinoma is the most common histologic finding, although adenocarcinoma, adenoid cystic carcinoma, and mucoepidermoid carcinoma make up about 20 percent. Lymph node metastases are uncommon.
Symptoms are usually rather diffuse, including nasal obstruction, local pain, epistaxis, and cheek swelling. Diagnosis is made by intranasal biopsy through a speculum or by antrostomy through the lateral nasal wall or labial buccal sulcus. The maxillary sinus is by far the most common site of origin of the disease.
Treatment of paranasal sinus tumors includes a combination of radiation therapy and surgery. Radiation therapy alone provides poor palliation and unacceptably low survival rates. Preoperative radiation therapy to 6000 cGy combined with radical surgery has been the usual approach, resulting in 3-year survivals in the vicinity of 1030 percent.
Surgical resection involves en bloc removal of the affected sinus and the surrounding involved structures. Total maxillectomy with or without orbital exenteration may be required for adequate clearance. Craniofacial techniques have improved the ability to safely remove tumors of the ethmoid and other paranasal sinuses and have increased 5-year survival rates to nearly 60 percent.
Reconstruction of the postoperative defect that has been irradiated previously is a difficult problem. Small defects can be obturated with nasal or dental prostheses. Larger defects, however, require three-dimensional reconstruction with free-tissue transfer.
The larynx is divided into three anatomic areas: the supraglottic larynx from the epiglottis to the ventricle; the glottic larynx, including the true vocal cords and the anterior commissures; and the subglottic area, surrounded by the cricoid cartilage. Carcinoma of the larynx is the most common malignancy of the upper aerodigestive tract. Nearly 10,000 new cases per year present in the United States. The risk for laryngeal cancer is directly proportional to the amount of exposure to tobacco, with a lesser relationship to alcohol intake. Increasing age is also a risk factor. Black patients have an increased risk of developing laryngeal cancer at a younger age. Exposures to asbestos, nickel, and wood dust are also likely cofactors. The relationship of papillomas in the etiology of laryngeal cancer is unclear.
Individuals with carcinoma of the glottic larynx are most likely to present with early-stage disease. The symptoms include hoarseness, other voice changes, tickling in the throat, and coughing. Evaluation includes indirect laryngoscopy as well as physical examination of the neck. The geographic site and extent of the lesion, whether confined to the larynx or spreading beyond, are of importance. The mobility of the vocal cords is also crucial because it represents invasion of tumor into deeper structures of the larynx. CT scans and MRI are useful in documenting invasion of the thyroid cartilage. Biopsy can be performed with a rigid laryngoscope to clearly define the extent of disease.
Individuals with supraglottic carcinoma of the larynx are more likely to present with advanced-stage disease. Micrometastases are common despite a clinically negative neck. Patients with inadequate primary therapy for supraglottic carcinoma are more likely to fail from recurrence in the neck and distant metastases than from local recurrence alone.
The vocal cords are a small area that is in constant use and regularly exposed to carcinogenic stimuli. Tumors in this area usually behave indolently. When these tumors extend outside the glottis, a more aggressive pattern is noted. Early symptoms are noticeable with glottic cancer, making them more amendable to less radical therapy. The low likelihood of clinically evident or micrometastatic nodal disease also makes glottic cancer more suitable for less radical treatment.
Subglottic carcinomas are rare, making up only 12 percent of all laryngeal carcinomas. They tend to spread by submucosal extension down the trachea, and patients frequently present with advanced-stage local disease. Cervical metastases are not very common. Radical combined therapy, i.e., surgery and radiation therapy, is necessary. The significant factors for survival include presence of lymph node metastases, advanced local disease, vocal cord fixation, histologic grade, ulceration, and male gender.
In glottic cancer, radiation therapy has become the accepted treatment for most early squamous cell carcinomas. Conventional radiotherapeutic techniques deliver doses of 6000 cGy over 6 weeks. This results in a cure rate of 8090 percent for T1 carcinoma and 7090 percent for T2 lesions. More advanced lesions also have been approached with standard radiation therapy in doses of 65007700 cGy. Many of these patients will require surgical salvage. Such high-dose radiation therapy results in significant complications, including laryngeal edema and chrondronecrosis. Early lesions of the glottis that involve the mobile cord and do not extend to the anterior or posterior commissures may be treated with vocal cord stripping. T1 lesions of more bulk but confined to one cord may be removed by cordectomy, a procedure that is usually performed by opening the larynx rather than endoscopically.
The conventional therapy for cancers that cross the anatomic boundaries of the supraglottis and glottis, so-called transglottic lesions, is a total laryngectomy. Depending on the presence of palpable lymph nodes or suspicion of metastatic disease, radical or modified radical neck dissection may be indicated. Disease-free margin status is the most reliable predictor of local control. When total laryngectomy is used as definitive therapy for advanced-stage disease, 5-year survival rates of 60 percent for T3 and 50 percent for T4 lesions have been reported.
Voice preservation can be attempted in two ways: conservation surgery, i.e., removing only part of the larynx, and reconstruction of a voice-preserving mechanism after total laryngectomy. Lesions confined to one part of the larynx can be removed, leaving enough larynx behind to allow speech that is superior to mechanical speech. Conservation surgery is appropriate in patients in whom lesions are less than 3 cm, the vocal cords are mobile, and a margin of 5 mm is possible. Also, there should be no cartilage or preepiglottic space invasion, and tongue mobility should be normal.
Mechanical voice restoration after surgery that removes the entire larynx is a difficult problem. Only 2545 percent of alaryngeal patients acquire esophageal speech. Inability to expel air from the stomach and other physiologic reasons have been cited for this failure. Mechanical devices inserted into the airway have been largely unsuccessful. External vibrators do allow intelligible speech of low volume. Various attempts have been described to create a neolarynx. A simple tracheoesophageal puncture described by Singer and Blom can be maintained patent by a small tube that allows pulmonary air to enter the esophagus, and thus the pharynx, and be modulated by the tongue, lips, and buccal mucosa. This method has allowed fluent speech restoration in 75 percent of patients with little risk of aspiration. Transplantation of the larynx has not been successful, but research is continuing with this method.
Complications of total laryngectomy include pharyngocutaneous fistulas, acid and food regurgitation, and stenosis. These complications are particularly associated with previous radiation therapy, malnutrition, and cell-mediated immunodeficiency.
Connective tissue neoplasms are uncommon and make up less than 1 percent of head and neck tumors. Fibrosarcoma is the most common of these lesions. Others include malignant fibrous histiocytoma, angiosarcoma, and rhabdomyosarcoma. Ten percent of osteogenic sarcomas arise in the head and neck.
Paragangliomas or chemodectomas are neoplasms in the head and neck that arise from neural crest cells and that histologically resemble their adrenal gland counterpart, the pheochromocytoma. They are classified by their location: carotid body, jugular, vagal body, orbital and laryngeal. Although these extraadrenal paraganglionic cells do contain a small amount of catecholamines, it is rare for them to produce a clinically significant excess of catecholamines. The carotid body tumor is the most common of the paragangliomas. It usually presents as an asymptomatic neck mass. Only 6 percent of these tumors are malignant. Paragangliomas are highly vascular and have a characteristic appearance on angiography. Treatment should include complete resection, which in the carotid body requires subadventitial dissection.
HIV infection produces a large number of abnormalities in the head and neck, both neoplastic and nonneoplastic. Immunosuppression allows opportunistic organisms to cause serious disease. Oral candidiasis may be one of the earliest manifestations of AIDS. Herpes simplex virus infection can result in painful ulcerations of the lips, oral mucosa, and oropharynx. Varicella-zoster infection is a painful syndrome with distribution along cranial nerve V.
Oral hairy leukoplakia is similar to leukoplakia in chronic smokers but is more likely to be seen on the lateral border of the tongue. This lesion may be an early sign of ultimate HIV infection, again as an expression of decreased immunosurveillance.
Lymphoproliferative disorders are characteristic of AIDS and frequently manifest themselves in the head and neck area. Obstruction of the nasal pharynx secondary to overgrowth in Waldeyer's ring has been reported. Cervical lymphadenopathy is commonly a part of the AIDS-related complex. Malignant lymphomas, most commonly of the B-cell type, also have been reported and are second only to Kaposi's sarcoma in frequency. T-cell lymphomas also occur but are less common. For disease localized to one area, radiation therapy may be an effective form of treatment. Multidrug systemic chemotherapy is also effective but places the already immunosuppressed patient at a higher risk of disseminated infection.
Kaposi's sarcoma is the most common malignancy in AIDS. The oral form of Kaposi's sarcoma occurs most commonly in the palate. Usually the distribution is multifocal. Tumor may arise in or metastasize to the cervical lymph nodes or the salivary glands. The tumor initially presents as a flat, blue to purple patch and may appear to be a submucosal hematoma secondary to trauma. Later in the course of growth it becomes nodular. Single-drug treatment with vinblastine or VP16, as well as with interferon alpha, has been used systemically or as an intralesional injection to treat Kaposi's sarcoma of the oral cavity.
Squamous cell carcinoma appears in HIV-infected patients at an earlier age and without the usual risk factors of smoking and ethanol intake. This pattern is suggestive of a defect in immunosurveillance similar to that seen in patients having undergone organ transplantation. The median age of presentation of squamous cell carcinoma of the oral cavity is 32 years. The clinical course seems to be somewhat more aggressive.
The major salivary glands are the symmetrically paired parotid, submandibular, and sublingual glands that discharge saliva into the oral cavity via Stensen's duct, Wharton's ducts, and the numerous small orifices in the floor of the mouth, respectively. The normal volume of salivary secretion in the adult male ranges from 10001500 mL/day, mainly as serous fluid from the parotid and submandibular glands. Immunoglobulins A, G, and M, albumin, lysozyme, and other enzymes also are secreted. In addition to its lubricating properties, which allow food to be moved through the mouth, saliva has antibacterial and antiviral properties that protect the soft tissues of the oral cavity as well as the teeth.
The parotid gland is located behind the mandible adjacent to the pterygoid muscles and extends into the preauricular area down to the angle of the mandible. The medial extent of the gland usually reaches over the masseter muscle and vertical ramus of the mandible. The gland is divided into the deep and superficial lobes by the facial nerve that exits from the stylomastoid foramen. Seventy percent of the parotid gland lies superficial to the plane of the facial nerve. Stensen's duct, the parotid duct, condenses from the large intralobular ducts and passes adjacent to the buccal branch of the facial nerve. It enters the oral cavity adjacent to the second maxillary molar tooth.
The facial nerve supplies motor intervation to the muscles of facial animation. On passing through the parotid gland, the nerve divides into an upper and lower division. The upper division usually includes the temporal, zygomatic, and buccal branches. The lower division includes the marginal mandibular and cervical branches.
The submandibular gland lies beneath the platysma muscle surrounded by the anterior and posterior bellies of the digastric muscle and the mandible. Wharton's duct conveys the secretions of the submandibular gland into the oral cavity.
Sublingual salivary glands lie immediately beneath the mucosa in the floor of the mouth intimately related to the lingual artery and release their secretions into the oral cavity through numerous orifices.
Inflammatory Disorders Inflammation usually presents as a diffuse enlargement or firmness. Bacterial infection is the result of duct obstruction and retrograde infection with oral bacteria. Acute bacterial parotitis may be seen in the elderly postoperative patient who becomes dehydrated and is usually caused by Staphylococcus aureus. Rehydration and antibiotic therapy are usually successful. Mumps, coxsackie virus, and echoviruses also may cause acute parotitis. Tuberculosis, actinomycosis, and cat scratch disease also may present with enlargement of either salivary glands or their adjacent lymph nodes. Systemic disorders such as sarcoidosis, Sjögren's syndrome, and cirrhosis with liver failure also result in salivary gland enlargement.
Tumors Of all salivary gland tumors, 70 percent are in the parotid gland. Of parotid gland tumors, 70 percent are benign, and of the benign tumors, 70 percent are pleomorphic adenomas. Pleomorphic adenoma is the proliferation of both epithelial and myoepithelial cells of the ducts as well as an increase in the stromal component. These tumors may grow to a large size without causing facial nerve symptoms. Pleomorphic adenoma usually presents as a solitary painless mass in the superficial lobe of the parotid. Malignant degeneration of pleomorphic adenomas occurs in 210 percent.
The second most frequent benign tumor of the parotid is the papillary cystadenoma lymphomatosum, or Wharthin's tumor. With a marked male predominance, this tumor usually occurs in the tail of the parotid gland and appears histologically as a lymphocytic infiltrate with cystic epithelial proliferation. There is a 10 percent incidence of bilaterality and multicentricity.
Malignant tumors of the salivary glands almost always present as a discrete mass. Pain is associated with malignancy in 20 percent of patients. Other symptoms include formication, facial nerve dysfunction, and complete paresis of the nerve. Facial nerve palsy is almost never seen with benign disease and must be considered a possible sign of malignancy. The risk of clinical or subclinical metastases to the cervical lymph nodes depends on the histology and grade of the primary tumor. High-grade mucoepidermoid carcinoma, adenocarcinoma, and squamous cell carcinoma have a high risk of metastatic disease, whereas adenoid cystic tumors and lower grades of mucoepidermoid and squamous cell carcinoma are at low risk of metastasis. In all, 20 percent of parotid gland neoplasms are malignant.
Diagnosis The discrete mass in the salivary gland must be considered a possible malignancy. History and physical examination provide important clues as to whether a salivary gland lesion is malignant. Complete resolution after a 10-day course of antibiotics is consistent with inflammation and constitutes an adequate therapeutic trial. FNA may be helpful for planning surgical excision. MRI gives the best anatomic information about tumor size and penetration. Sialography, or injection of contrast material into Stenson's or Wharton's ducts, is useful in demonstrating chronic stenotic changes of benign lymphoepithelial lesions versus occlusion from stones. Eighty percent of parotid duct stones are radiolucent. Eighty percent of submandibular gland stones are radiopaque.
Treatment The surgical approach to a salivary gland mass is predicated on the assumption that it is malignant. The major problem is the presence of the facial nerve in the parotid gland. If there is no evidence of nerve involvement, the tumor should be excised by superficial lobectomy, preserving the nerve. If the tumor is malignant, total parotidectomy with preservation of the nerve is indicated, although it is a piecemeal procedure. Involvement of a branch of the nerve or the whole nerve requires removal. Replacement of the resected segment of nerve using a nerve graft can avoid the sequelae of facial nerve palsy.
When clinical examination with or without FNA does not clearly define the problem, biopsy should be obtained by superficial lobectomy. Benign tumors can be removed with a clear margin by superficial lobectomy. Involvement of the deep lobe requires total parotidectomy.
Treatment of the regional lymph nodes depends on the histologic type and grade of the tumor. Clinically node-positive necks are treated with an appropriate neck dissection. Elective or prophylactic neck dissections are not as frequently necessary as in other head and neck malignancies. High-grade mucoepidermoid or squamous cell carcinoma and high-grade adenocarcinoma are exceptions that warrant ipsilateral neck dissection.
Neoadjuvant or adjuvant chemotherapy has been effective in salivary gland malignancies. Postoperative radiation therapy, however, is effective. Radiation portals should include the site of surgery, the foramen ovale, the base of the skull, and the ipsilateral neck.
Adenoid cystic carcinoma is the most common malignant histologic finding in the submandibular gland, whereas pleomorphic adenoma is the most common benign tumor of this gland. Adjuvant postoperative radiation therapy appears to be helpful for these uncommon malignancies.
Tumors of the minor salivary glands, either benign or malignant, are most common in the hard and soft palate. Their presentation may be as submucosal or ulcerative masses. Pleomorphic adenoma is the most common benign tumor, and mucoepidermoid and adenoid cystic carcinoma are the most common malignancies. Treatment is wide local excision including the subjacent bone, with adjuvant radiation therapy reserved for malignant cases. Lymph node metastases are rare.
For a more detailed discussion, see Coleman JJ, Sultan MR: Tumors of the Head and Neck, chap. 15 in Principles of Surgery, 7th ed.
Copyright © 1998 McGraw-Hill
Seymour I. Schwartz
Principles of Surgery Companion Handbook