Subungual malignant melanoma: a clinical-pathologic study.

In a study of 66 cases of subungual malignant melanoma, a clinical misdiagnosis often delayed histologic diagnosis and proper treatment. Most subungual melanomas are deep lesions at the time of histologic examination. Female patients have a relatively good prognosis as opposed to the poor prognosis of male patients. Paradoxically, a few patients with relatively shallow tumors and low mitotic rates died with metastases and a few patients with deep aggressive-appearing melanomas are alive and well more than five years later. Metastases, however, may become evident many years after the primary tumor has been resected. Metastases to the regional lymph nodes may be found at the time of amputation but do not preclude a long survival. No difference in prognosis related to the extent of the amputation could be identified. A variety of histologic patterns may be present and the adjacent epidermis frequently shows changes of precancerous melanosis but the survival is not affected.