HISTOGENETICAL PECULIARITIES OF MALIGNANT SKIN MELANOMAS

With the purpose of investigating the histogenesis of malignant skin melanoma, 194 cases were studied in which the tumor was fully represented in a microscopic slide and the behavior of melanoblasts could be observed above the tumor, at its edges and on both sides of it. Intense proliferation of melanoblasts of the epidermis, accompanying the migration (« Abtropfung ») of the cells into the derma, was found in 82 out of 194 operated patients with malignant melanomas. Such neoplasms usually had the appearance of a spot or infiltrate and were most frequently localized on the lower extremities. The tumors of this kind were defined as epidermo-dermal malignant melanomas. In 112 cases the tumors were of another pattern. Junctional melanoblasts did not participate in their formation; they developed from cells located only in the derma and originating from cells of intradermal nevi. They had typical growth in the form of a pedunculated nodule or of a nodule on a broad base; most frequently they were localized on the trunk. Tumors of this kind were defined as intradermal malignant melanomas.