mastocytoma

A fairly well-circumscribed accumulation or nodular focus of mast cells, grossly resembling a neoplasm. [mastocyte + G. -oma, tumor]

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mas·to·cy·to·ma .mas-tə-.sī-'tō-mə n, pl -mas also -ma·ta -mət-ə a tumorous mass produced by proliferation of mast cells

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mas·to·cy·to·ma (mas″to-si-toґmə) [masto- + cytoma] a nodular cutaneous mast cell infiltrate, usually present at birth or soon after as a solitary nodule, although three to four lesions may occur. Lesions typical of urticaria pigmentosa may occur later. Called also mast cell tumor.

Mastocytoma. (A), Solitary mastocytoma in a child; (B), Giemsa stain reveals purple granules characteristic of mast cells in the dermis.