Melanoma

Malignant melanoma cells may vary in size and shape and mimic other non-hematological tumors like sarcomas or carcinomas but also lymphomas or plasma cell myelomas. Generally the cells lie separately and do not form clusters. Cells can be pleomorphic, small cells, spindle cells, plasmacytoid, ballooncells or giant cells. Nuclei generally are round to ovoid, but can be bi- or multilobulated. Chromatin is generally fine and dense reticular and mitotic figures are almost always found. The finding of black melanin is essential for diagnosis, this can be found as dark granules in all quantities, sizes and patterns.