An uncommon vascular, usually benign, neoplasm composed of round and spindle cells that are derived from the pericytes and surround endothelium-lined vessels; malignant hemangiopericytomas are difficult to distinguish microscopically from the benign. [hemangio- + pericyte + G. -oma, tumor]
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hem·an·gio·peri·cy·to·ma or chiefly Brit haem·an·gio·peri·cy·to·ma -jē-ō-.per-ə-.sī-'tō-mə n, pl -mas also -ma·ta -mət-ə a vascular tumor composed of spindle cells that are held to be derived from pericytes called also perithelioma
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he·man·gio·peri·cy·to·ma (he-man″je-o-per″ĭ-si-toґmə) [hemangiopericyte + -oma] a tumor composed of spindle cells with a rich vascular network, which apparently arises from pericytes. It may be benign or malignant and usually occurs in the lower extremities or retroperitoneum.Medical dictionary. 2011.