AMELANOTIC MALIGNANT-MELANOMA PRESENTING AS MALIGNANT SCHWANNOMA

A 78-year-old woman presented with a 14-month history of a nodule on t he sole of her left foot. It had been increasing in size, and had beco me ulcerated. Histological, immunochemical and ultrastructural studies of the primary tumour revealed melanocytic and Schwannian characteris tics, and posed diagnostic difficulties. The final diagnosis of a mali gnant melanoma with Schwannian differentiation was established on the basis of the clinical course, with the development of metastases in th e subcutis, lymph nodes, liver and brain. as well as a shift in differ entiation of the metastases towards cells containing giant melanosomes , typical of melanoma.