has part has part has_part characteristic of abnormal bone structure bone fibrous dysplasia 2022-02-01T10:29:40Z fibro-osseous lesions normal bone and marrow is replaced with scar-like (fibrous) connective tissue, resulting in formation of bone that is weak and prone to expansion MPheno.ontology MP:0031348 Per NIEHS pathologists, fibro-osseous lesions (FOLs) are characterized by proliferation of stroma (supportive tissue consisting of connective tissue and blood vessels) with proliferation of osteoblasts and osteoclasts cell populations. According to the Nonneoplastic Lesion Atlas, FOLs show partial or complete replacement of bony trabeculae and marrow cavity by fibrovascular stroma containing fibroblasts, osteoclasts, and osteoblasts embedded in eosinophilic matrix. The histopathologic features are similar to fibrous osteodystrophy; however, FOLs occur in the absence of parathyroid or renal alterations, typically arise as focal lesions within the metaphyseal or endocortical regions, and may progress to involve larger areas of the bone. fibrous dysplasia of bone bone element