Fibro-osseous dysplasia of temporal bone

THE aetiology of fibro-osseous hyperplasia is not known. Possible abnormality in development, faulty repair after minor trauma, chronic infections, are some of the factors considered to be responsible, but none is conclusively proved. Mono-ostotic, where one bone is involved and poly-ostotic when similar lesions are found at multiple sites in the skeletal system, are the two types recognized. Behaviour of this disease is unlike a true neoplasm as the growth of the tumour is arrested after puberty. In the process of this disease normal bone is replaced by fibrous tissue in varying proportions. The histological section shows abundance of fibroblasts in interlacing bundles or in whorls. The connective tissue stroma which is relatively vascular contains islets of irregular trabeculae of newly-formed bone. McCart mentions that focal nature of the disease is an important diagnostic feature, the uninvolved part of the bone retaining its normal structure. Unlike the fibrous dysplasia of parathyroidism, blood chemistry findings are essentially negative. Serum calcium, serum phosphorus and alkaline phosphatase are within normal limits. Negative calcium balance does not occur. Jaw bone, i.e. maxilla or mandible, is frequently affected. Several cases appear in the literature from time to time but involvement of the temporal bone is rare. On the whole, bony growths of temporal bone are uncommon. In the past, therefore, only a few cases of fibro-osseous hyperplasia of the temporal bone are recorded in the literature.