Fig. 6

Other epithelioid malignant neoplasms of uncertain histogenesis. a–d Classic-type epithelioid sarcoma (ES). Classic-type ES consists of vague nodules of epithelioid tumor cells with moderately abundant pale eosinophilic cytoplasm and mild cytologic atypia, with a central zone of necrosis which mimics necrobiotic granulomatous lesions from lower power magnification (a, b). The epithelioid cells are positive for EMA (c) and show nuclear loss of INI1 (d). e, f Proximal-type ES often shows a greater degree of coagulative-type necrosis and consists of sheets of larger cells with vesicular chromatin and prominent nucleoli (e, f) but show a similar immunohistochemical profile to classic-type ES. g, h Cutaneous clear cell sarcoma (CCS). CCS consists of nests of plump epithelioid and spindled cells containing abundant clear or pale eosinophilic cytoplasm and uniform ovoid nuclei with vesicular chromatin and prominent nucleoli (g). Thick, hyalinized collagen bundles separate the nests (h), which can be a useful morphologic feature to distinguish from melanoma