Intermediate Filaments in Malignant Melanomas IDENTIFICATION AND USE AS MARKER IN SURGICAL PATHOLOGY

studied in human malignant melanomas and in normal melanocytes by immunofluorescence microscopy with antibodies directed against keratin, vimentin, desmin, neurofilament protein, and glial filament protein. Both human melanotic and amelanotic tumor cells and tu-mor metastases as well as normal melanocytes in hu-man skin and in the rat eye contain exclusively inter-mediate filaments of the vimentin type. No reaction was seen with antibodies to keratin, desmin, neurofil-aments, or glial filaments. These latter four antisera, however, gave strong reactions in epidermis and other epithelial tissues, muscle, or neural tissues, respec-tively. The results favor a mesenchymal character of melanocytes, although a neuroectodermal origin in an early developmental stage is possible. The finding that melanomas contain exclusively vimentin intermediate filaments may prove useful in differential diagnosis of melanomas from other tumor types