Repeated surgical reduction of the mandible over a 19-year period due to fibrous dysplasia: A case report

Fibrous dysplasia is a benign bone lesion characterized by the replacement of normal tissue by fibro-osseous lesions with immature remodeling, which is now thought to be caused by GSα somatic mutation. The disease usually manifests early in life, and its growth is terminated in adulthood. Its malignant transformation is very rare. In the current report, a case of fibrous dysplasia of the mandible undergoing repeated surgery with a long-term follow-up duration is described. After the initial surgery performed at the age of 19 years, surgical reduction was performed eight times with an interval of 1–4 years over a 19-year course. At the age of 38 years, the lesion was still growing, while serum alkaline phosphatase remained within the normal range throughout the entire course. There was no evidence of malignancy on pathological examination. Immunohistochemistry using antibodies detecting bone morphogenetic proteins 2, 4, 6, and 7 (BMP-2, 4, 6, and 7) in order to assess bone growth activity showed positive staining for BMP-4 and 6, which are important markers of bone quality. Examining the expression of different BMP subtypes is useful for characterizing the bone-forming nature of fibrous dysplasia.