Spontaneous regression of human malignant melanoma.

Cellular and subcellular changes and cell-mediated immunity of a patient (a 26-year-old man) with spontaneously regressed malignant melanoma are described. The patient developed black nodules on his left leg and foot several times over a period of 11 years. These nodules necrotized, regressed to form crusted nodules and disappeared leaving white macules. Many melanin-laden cells (so-called melanophages) were seen in the upper dermis of the melanotic macules, and no melanoma cells were observed in the upper dermis of the white macules which appeared at the site of regressed melanotic macules or nodules. In melanin-laden cells observed in melanotic macules, many melanosome complexes with hydrolytic enzyme activity and a small number of single melanosomes were recognized. We assumed that some or many of the melanin-laden, melanophage-like cells in the upper dermis of a regressing malignant melanoma might be effete melanoma cells. Cell-mediated immunity had been preserved while spontaneous regression of tumors was occurring. However, the patient died as a result of metastatic melanomas which involved the lymph nodes, liver, bones, brain, heart, kidney, lung and gastrointestinal tract.