The melanin in a dark skin protects it from the effects of sunlight, with the result that basal cell carcinomas, which are common in the exposed areas of white skins (including particularly albino Africans as in A, Fig. 32-6), are very rare in black ones. The earliest stage is a raised nodule, but the usual presentation is for an old, or middle-aged, man to complain of a small ulcer on his face or scalp, commonly near his eye, which continues to break down and never really heals. It has a raised rolled edge, grows slowly, and eventually erodes into muscle, cartilage, or bone. Growth is slow and metastases do not occur. Prognosis is excellent for lesions treated early, whether by surgery or radiotherapy.
BASAL CELL CARCINOMA THE DIFFERENTIAL DIAGNOSIS includes acanthosis senilis, tuberculosis of the skin, and fungal lesions.
TREATMENT. For very small lesions, radiotherapy offers no advantages over surgery, because the diagnosis has to be confirmed by biopsy anyway; for middle-sized or large ones it is of some cosmetic value.
Excise the lesion with at least 1 cm of normal tissue all round it, which may be difficult if it has spread extensively. It will not spread to the regional lymph nodes, so there is no need to excise these. Send a specimen for histological examination.
Fig. 32-6 CARCINOMAS OF THE SKIN, squamous cell carcinoma and basal cell carcinoma. A, this albino has already had several squamous carcinomas. One has eroded his skull; it was successfully excised, and his dura grafted, leaving a large depression. Another large one has now destroyed his ear. B, another albino with a large basal cell carcinoma (rodent ulcer) of the side of his face. C, a squamous cell carcinoma in the leg. Note its raised edges. D, an X-ray of the same lesion, showing bone destruction and sclerosis. B, after Charles Bowesman, ''Surgery and Clinical Pathology in the Tropics'', E and S Livingstone, with kind permission.