Basal cell carcinoma of the sole.

Basal cell carcinoma (BCC) of the plantar surface of the foot is rare, with only 22 previously reported cases. This clinicopathologic study is based on 20 cases of BCC of the plantar surface and plantar-like surfaces from adjacent lower lateral and medial aspects of the foot, submitted to a large podiatric laboratory from 1986 through June 1992 (total specimens for this period = 518,624; total BCC of lower extremities, below knee = 53). There were 15 women and 5 men. The average patient age was 73 years, with a range from 52 to 92 years. The duration of the lesion before diagnosis was 2 months to 12 years, with an average of 2 years. Three patients had a history of trauma. Podiatric clinical diagnoses included BCC (4), SCC (3), soft tissue tumor (2), nevus (1), granuloma (1), keratosis (2), verucca (1), and psoriasis (1). Follow-up information was available on 10 patients; all were free of disease up to 64 months, with an average follow-up of 15.7 months. Three of 20 BCC showed predominant histologic patterns characteristic of fibroepithelioma of Pinkus (FEP). An additional three BCC showed focal or suggestive patterns of FEP. Fourteen tumors showed ordinary BCC histologic patterns. No multicentric-superficial or morphea like BCC were observed. The relatively high incidence of FEP in BCC of the sole correlates with abundant sweat glands and lack of hair follicles on the plantar surface, in accordance with the recent proposal that FEP derives its histologic pattern from the spread of BCC down eccrine ducts, eventually replacing them with solid strands of tumor.