Skin Disorders Guide

Diagnostic Hallmarks

1. Distribution - sun-exposed portions of the face and ears
2. Occurrence against a background of sun-damaged skin
3. Rolled border, translucent appearance

Clinical Presentation

Basal cell carcinomas appear as smooth-smfaced, skin-colored, somewhat translucent (”pearly”) papules. Lesions 4-6 mm in size are flat-topped with rounded or rolled shoulders. Those 6-8 mm in diameter usually show a central dimpling. Larger lesions frequently have a central ulceration. Telangiectatic vessels are sometimes found on the shoulders of the lesion. The papules are firm on palpation, but bleed easily following even minor trauma. They are otherwise asymptomatic. Basal cell carcinomas grow very slowly, and patients will sometimes claim that they have been present unchanged for a year or more. Nearly all basal cell carcinomas are found on the sun-exposed surfaces of the face and ears. An occasional lesion develops on sun-damaged skin of the hands, arms, and shoulders. They are rarely seen before age 40. Clinically suspicious lesions should be positively identified by biopsy.

Uncommon clinical Presentatians. The nevoid basal cell carcinoma syndrome (also known as the basal cell nevus syndrome) is a familial syndrome consisting of multiple basal cell carcinomas, keratotic pits on the palms, keratinous cysts of the jaw, skeletal abnormalities, cerebral calcification, and a variety of soft tissue tumors. The development of multiple basal cell carcinomas prior to the age of 50 or a family history of basal cell carcinomas should alert the clinician to the possibility of this syndrome.

Superficial basal cell carcinomas are clinically quite distinct from the papular and nodular lesions described above. They are very similar to the sharply marginated, red plaques of Bowen’s disease. Both of these in situ carcinomas are listed with the papulosquamous diseases.

Course and Prognosis

Basal cell carcinomas, left untreated, inexorably enlarge. Centrifugal growth is accompanied by deep invasion of the dermis and, eventually, of subcutaneous structures. Response to early treatment is excellent. Five-year cure rates of 95-100% are obtainable. Metastases to regional lymph nodes, bone, and lungs occur in less than 1 % of patients.

Pathogenesis

Basal cell carcinomas arise from relatively nondifferentiated epithelial cells of the basal layer of skin and skin appendages. The induction of this proliferative response seems to depend primarily on damage done by long-term ultraviolet light exposure. Generally, the factors responsible for the appearance of basal cell carcinoma are almost identical with those responsible for the development of actinic keratoses . New data suggest that the development of sporadic basal cell carcinomas, as well as those that occur in the nevoid basal cell carcinoma syndrome, are accompanied by mutations of a tumor suppressor gene located on chromosome 9.

Therapy

Basal cell carcinomas less than 2 cm in diameter can be successfully treated in several ways: excisional surgery, curettage and electrosurgery, radiation therapy, and cryosurgery. All four approaches result in initial clearance rates of better than 90%, and when retreatment for recurrence is added, ultimate cure rates of 98% or better can be obtained. Excisional surgery has the advantage of furnishing a complete specimen that may be histologically checked for adequacy of removal. Cryosurgery and curettage with electrosurgery offer simplicity, speed, and low cost. Radiation therapy results in the least tissue destruction. In addition to the established forms of therapy discussed above, there have been exciting recent reports suggesting that intralesionally injected interferon may offer a highly efficacious nonsurgical approach to the treatment of these tumors. The choice of modality used depends on the size and location of the lesion, the age of the patient, patient preference, and skills of the operator.

Recurrent lesions and initial lesions larger than 2 cm in diameter are best treated by the use of microscopically controlled surgery. This approach, termed the Mohs micrographic surgery, results in maximum conservation of tissue and extraordinarily high cure rates.