Chapter 13 Skin and
Principles of Surgery Companion Handbook
SKIN AND SUBCUTANEOUS TISSUE
|Functions of Skin|
Tension and elasticity are the primary physical properties of the skin.
is the characteristic that accounts for the fact that skin can resist stretching. Tension is most
is the resistance of skin to
Functions of skin include (1) percutaneous
This function of skin
Percutaneous absorption of phenol and carbolic acid is rapid and may cause fatal
Substances in gas form, with the exception of carbon monoxide, penetrate the skin easily. This method has been employed pharmaceutically with the use of dimethylsulfoxide (DMSO) as a vehicle.
Local vascular response may result from direct action on the vessel wall or its contractile elements. A red local reaction can develop after dilatation of small vessels. A
is a circumscribed area of skin edema secondary to dilated blood vessels and leakage of plasma into the extracellular space. Conversely, stimulation of sympathetic
Causalgia is a syndrome of pain and vasodilatation that occurs after
Sweat Secretion Sweat glands in skin are eccrine glands or apocrine glands. The eccrine glands are distributed all over the body and are primarily responsible for heat regulation. The apocrine glands are similar to sebaceous glands and develop mostly during puberty. Their activity is in response to autonomic nervous stimulation rather than thermal conditions.
Sweating is a response to local application of heat or to nervous impulses. Sympathetic nerve fibers liberate acetylcholine to stimulate sweat glands. Atropine and other anticholinergic drugs can block these receptors and interfere with sweat secretion. Hyperhidrosis results from an abnormal increase in nerve impulses or emotional states.
The content of sweat is primarily water with small amounts of sodium chloride. Potassium also is lost through sweat. Nitrogen
Insensible Water Loss
Besides sweat secretion, water is lost through the epidermis by continuous evaporation. In contrast to sweat, water lost through evaporation does not contain electrolytes or other solutes. Approximately 700 mL total water loss occurs through the skin each day. Hypothyroidism decreases the daily amount of water loss, whereas
Regulation of body temperature is an important function of the skin. Heat
Thermoregulation is accomplished in skin also by shifting blood flow from the interior to the skin. Cold stimuli result in pallor of the skin by relative vasoconstriction. After the stimulus has ceased, there is a reactive arterial vasodilatation. This results in a reddish discoloration of skin. In contrast, prolonged cold stimulus causes paresis of the
Heat exhaustion is a syndrome of excessive loss of salt and water during exposure to high
Pressure on an area of skin for 2 h or more may result in ischemia sufficient to cause a pressure sore. Factors contributing to pressure sores include skin over bony prominence, anemia, malnutrition, and immobilization. Surgical
Hidradenitis suppurativa is a chronic infection of the cutaneous apocrine glands, subcutaneous tissue, and fascia. This disease occurs in the axilla, areola of the nipple, groin, or perineum. Commonly, there is
Definitive treatment requires complete
Epidermal Inclusion Cysts
An epidermal inclusion cyst results from epithelium of skin that is trapped subdermally because of trauma or other reasons and begins to grow and desquamate. The cyst is filled with keratin and desquamated
Sebaceous glands are associated with hair follicles and are generally found on the midline of the trunk and on the face. A cyst is
Dermoid cysts are congenital lesions that arise in early childhood. They generally occur in the midline of the body, on the lateral eyebrow, on the scalp, or in the abdominal and sacral
Pilonidal cysts are malformations of the neuroenteric canal that occur in the sacrococcygeal region. The ingrowth of hair in the coccygeal region sets the stage for cyst formation and repeated infections. This disease has been referred to as jeep driver's disease because long hours of sitting and bumpy driving aggravate the congenital condition. Chronic infection and drainage are the usual presentation. Treatment includes incision and drainage followed by secondary removal of the cyst or sinus when infection has subsided. Excision of the entire sinus is essential for successful treatment. This may be facilitated by injection of methylene blue to determine the extent of arborization of the sinus
Ganglia are areas of mucoid degeneration in retinacular structures. They are
Warts Verruca vulgaris, the common wart, is caused by a contagious virus. Warts usually occur on the hand or soles of the feet. They are quite tender and painful.
Treatment of verruca vulgaris can be accomplished with liquid nitrogen freezing or electrodesiccation under local anesthesia. Caustic agents also have been used but result in a higher recurrence rate.
Keratosis Keratosis is a precancerous lesion manifested by hypertrophy of the epidermis. Senile keratoses occur in older individuals with a fair complexion. They should be treated by surgical excision if the lesion is large and the suspicion of malignancy is low. Topical treatment with 5-fluorouracil or liquid nitrogen may be done.
Seborrheic keratosis is a thickened area of skin that may appear brown, gray, or black. Occasionally these lesions are mistaken for melanoma. Electrocoagulation is adequate treatment.
Keloids are dense accumulations of fibrous tissue that extend above the surface of the skin from traumatic wounds or surgical
First-line treatment of keloids is steroid injection. This method is effective in
Capillary malformations are commonly known as
of the skin. They represent dilated abnormal capillaries in the subdermal plexus. They are smooth lesions with reddish or purplish patchy distribution. Excision of small lesions is appropriate. The larger lesions are now being treated with laser. This is reserved, however, for patients over 14
Arteriovenous malformations are also called
These lesions are evident at birth and do not change during growth of the child. Occasionally, they involve deep structures such as the central nervous system or
Glomus tumor is a rare benign neoplasm of the skin that usually occurs in the nail beds of the hands and feet. These lesions are extremely painful because they are derived from the glomic end organ, a nerve apparatus that normally functions to regulate blood flow in the extremity. These lesions are also called
and generally are benign. The malignant
Neurofibromas and Schwann
Skin cancer is associated with exposure. Ultraviolet light, ionizing radiation, and chemicals are causative factors. Skin cancer usually is manifested by a low-grade malignant tumor that metastasizes late. Therefore, cure rates of
Squamous Cell Carcinoma
Squamous cell carcinoma usually
Squamous cell cancers are found in areas of frequent irritation such as the vermilion border of the lip, areas of postirradiation dermatitis, or ulcerations in old burn scars. Bowen's disease is a slowly growing squamous cell carcinoma in situ for which excision is recommended.
Sweat Gland Carcinoma
This rare tumor usually occurs in the
Options for treatment of skin cancer include electrodesiccation, cryosurgery, chemosurgery, radiation therapy, and surgical therapy. Biopsy of the skin lesion and relevant history determine the choice of therapy. Electrodesiccation and curettage are
Approximately one-third of patients with positive margins after resection of basal cell carcinoma will develop recurrence. If the patient is reliable, simple observation may be all that is indicated. Repeat surgical excision is the best treatment for recurrence.
Eighty percent of squamous cell carcinomas are cured by surgical excision. Mohs has
Fibrosarcoma This tumor occurs commonly in women in the thigh, buttock, or inguinal region. It usually is a relatively low-grade malignancy and is radioresistant. Wide surgical excision is the treatment of choice. Local recurrence is common.
This is a malignant tumor of angioblastic origin and is probably a variant of the glomus tumor.
Kaposi's Sarcoma This tumor has a markedly increased incidence in homosexuals. Acquired immune-deficiency syndrome (AIDS) is commonly associated with Kaposi's sarcoma. Usually, the tumor begins in the hands or feet as multiple plaques that are reddish to purple and may be flat, ulcerated, or polypoid. Lymph node involvement is common. Radiation can retard the growth of Kaposi's sarcoma, but surgical excision is also helpful. Actinomycin D has produced some positive responses. Overall, the prognosis is poor.
Dermatofibrosarcoma Protuberans This tumor is a relatively low-grade malignancy that generally occurs on the trunk. It is radioresistant but responds to surgical excision with a 70 percent 5-year disease-free survival.
Intradermal nevus, junctional nevus, and compound nevus are examples of benign pigmented lesions; however, they have variable degrees of malignant potential. The intradermal nevus is a nest of melanoblasts confined to the dermis. Frequently, these nevi contain hair. The junctional nevus is a
The differential diagnosis between benign pigmented skin lesions and melanoma can be difficult. Changes in various characteristics of pigmented lesions are
The Hutchinson freckle (lentigo maligna) is a precancerous melanosis of the face that usually occurs in elderly people. Approximately one-third of these lesions will become malignant melanoma. Prognosis is
Melanoma is a malignant lesion originating in the melanoblast of the skin. Mucous membranes and pigmented regions of the eye also can harbor primary melanoma. The lesion is usually darkly pigmented, smooth, firm, and nonhairy. At some phases of development the melanoma cells do not contain melanin and are referred to as amelanotic melanoma.
TNM Classification for Staging of Melanoma
The T classification refers to primary tumor thickness. T1 includes lesions 0.75 mm or less in
The stage grouping is divided by involvement of nodes. Stage I is smaller tumors (T1 and T2) with negative lymph nodes, Stage II is larger tumors (T3 and T4) with negative lymph nodes, Stage III is any tumor size with positive lymph nodes, and Stage IV is any tumor with positive
The incidence of melanoma is increased by exposure to solar radiation in light-
Pathology Melanomas usually arise in nevi that have junctional activity. Nevi of the palms, soles, nail beds, genitalia, and mucous membranes have functional elements that make them more prone to be the source of melanoma than moles at other sites. Malignant melanoma rarely occurs in prepubertal children.
Four types of melanoma are described: superficial spreading melanoma, nodular melanoma, lentigo maligna melanoma, and acral lentiginous melanoma. Superficial spreading melanoma is characterized by intradermal spreading and accounts for almost 70 percent of all cutaneous melanomas. Nodular melanoma is less common and is characterized by little radial growth but more invasive growth. The prognosis for nodular melanoma is significantly
Surgical Treatment Surgical excision is the primary therapy for melanoma. For most pigmented lesions, an excisional biopsy with a margin of 2–5 mm is indicated. However, extremely large lesions may require an incisional biopsy, which is appropriate prior to planning definitive therapy.
The acceptable margins for definitive excision of melanomas depend on the thickness of the lesion. A margin of 0.5 cm is adequate for lesions less than 0.75 mm thick. Lesions between 0.76 and 1.5 mm thick require a 2-cm margin. Thicker lesions require a 4-cm margin. Amputation of a digit is indicated for acral lentiginous melanomas.
Removal of regional lymph nodes should be performed when there is clinical evidence of adenopathy and no distant metastases. Prophylactic dissection of regional lymph nodes is more
Some retrospective studies show a survival advantage for immediate lymph node dissection of clinical Stage I melanoma. A prospective, randomized study by the World Health Organization, however, showed no survival improvement for patients in this category. A
Regional Chemotherapy and Hyperthermia
Isolated regional perfusion has been
Immunotherapy A number of agents have temporarily controlled cutaneous metastases of melanoma. Local intralesional injections of bacille Calmette-Gurin provided remission in approximately 20 percent of patients in one study. Systemic treatment with biologic response modifiers has begun to show some impact on disseminated melanoma. Interferon has proved to be effective in a small percentage of patients.
Prognosis Prognosis for patients with melanoma depends on the staging. The 5-year cure rate for Stage I lesions smaller than 0.76 mm is almost 95 percent. Lesions between 0.76 and 1.5 mm have an 85 percent 5-year cure rate. Stage II lesions are less favorable, with a 60 percent 5-year survival rate. Patients who are Stage III (positive lymph node involvement) have approximately 35 percent 5-year survival.
For a more detailed discussion, see Young DM, Mathes SJ: Skin and Subcutaneous Tissue, chap. 13 in Principles of Surgery, 7th ed.
Copyright 1998 McGraw-Hill
Seymour I. Schwartz
Principles of Surgery Companion Handbook