Case for diagnosis
Twenty-seven year old female patient, phototype V, presented a lesion in the right arm\nfor one and a half years, without associated symptoms. Dermatological examination\nrevealed a smooth-surfaced, brownish, painless nodule, movable within deep layers,\nmeasuring three centimeters and located in the right arm (). Pathological examination of the surgical specimen showed dense\nproliferation of large cells with granular-appearing eosinophilic cytoplasm, distinct\nmembranes, central or eccentric nuclei and slightly conspicuous nucleoli. The neoplastic\ncells formed syncytia in some areas and were inserted within the interstices of a\ndesmoplastic stroma, with scarce focal lymphocytic infiltration. The results of\nimmunohistochemical examination were positive for S100 protein, CD63 and CD68 ().