Basal cell carcinoma is a superficial, slowly growing papule or nodule that derives from certain epidermal cells. Basal cell carcinomas arise from keratinocytes near the basal layer and can be referred to as basaloid keratinocytes. Metastasis is rare, but local growth can be highly destructive. Diagnosis is by biopsy. Treatment depends on the tumor's characteristics and may involve curettage and electrodesiccation, surgical excision, cryosurgery, topical chemotherapy, or, occasionally, radiation therapy.

Basal cell carcinoma is the most common type of skin cancer, with > 800,000 new cases yearly in the US. It is more common in fair-skinned people with a history of sun exposure and is very rare in blacks.

Symptoms and Signs

The clinical manifestations and biologic behavior of basal cell carcinomas are highly variable. They may appear as

• Small, shiny, firm, almost translucent nodules
• Ulcerated, crusted papules or nodules
• Flat, scarlike, indurated plaques
• Red, marginated, thin papules or plaques that are difficult to differentiate from psoriasis or localized dermatitis

Basal Cell Carcinoma

Most commonly, the carcinoma begins as a shiny papule, enlarges slowly, and, after a few months or years, shows a shiny, pearly border with prominent engorged vessels (telangiectases) on the surface and a central dell or ulcer. Recurrent crusting or bleeding is not unusual. Commonly, the carcinomas may alternately crust and heal, which may unjustifiably decrease patients' and physicians' concern about the importance of the lesion.

Basal cell carcinomas rarely metastasize but may invade healthy tissues. Rarely, patients die because the carcinoma invades or impinges on underlying vital structures or orifices (eyes, ears, mouth, bone, dura mater).

Diagnosis

• Biopsy and histologic examination

Treatment

Treatment should be done by a specialist. The clinical appearance, size, site, and histologic subtype determine choice of treatment—curettage and electrodesiccation, surgical excision, cryosurgery, topical chemotherapy (imiquimod, 5-fluorouracil, and photodynamic therapy), or, occasionally, radiation therapy. Recurrent or incompletely treated cancers, large cancers, cancers at recurrence-prone sites, and morphea-like cancers with vague borders are often treated with Mohs microscopically controlled surgery, in which tissue borders are progressively excised until specimens are tumor-free (as determined by microscopic examination during surgery). Almost 25% of patients with a history of basal cell carcinoma develop a new basal cell cancer within 5 yr of the original carcinoma. Consequently, patients with a history of basal cell carcinoma should be seen annually for a skin examination.

Last full review/revision October 2008 by Gregory L. Wells, MD