- A benign, slow-growing mass of mature, predominantly lamellar bone, usually arising from the skull or mandible. [osteo- + G. -oma, tumor]- o. cutis cutaneous ossification usually secondary to calcification in foci of degeneration in tumors or inflammatory lesions or, rarely, primary new bone formation in normal skin, often associated with Albright hereditary ostrodystrophy.- o. medullare an o. containing spaces that are filled (or partly filled) with various elements of bone marrow.- osteoid o. a painful benign neoplasm that usually originates in one of the bones of the lower extremities, especially the femur or tibia of adolescent and young adult persons; characterized by a nidus (usually no larger than 1 cm in diameter) that consists of osteoid material, vascularized osteogenic stroma, and poorly formed bone; around the nidus there is a relatively large zone of reactive thickening of the cortex.
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* * *n.a benign bone tumour. A cancellous osteoma (exostosis) is an outgrowth from the end of a long bone, usually rising to a point. A compact osteoma (ivory tumour) is usually harmless but it may rarely compress surrounding structures, as within the skull. An osteoid osteoma is an overgrowth of bone-forming cells, usually causing pain in the middle of a long bone. Compact and osteoid osteomas are treated by surgical excision.
* * *os·te·o·ma (os″te-oґmə) [oste- + -oma] a benign, slow-growing tumor composed of well-differentiated, densely sclerotic, compact bone, usually arising in membrane bones, particularly the skull and facial bones.
Medical dictionary. 2011.