Polyostotic Fibrous Dysplasia

Centered within the proximal left humeral diaphysis, there is an eccentrically located, cortically based T1-hypointense lesion with lobular margins. On the axial GRE weighted images, additional lesions are identified within the glenoid neck. The lesions are T2/STIR hyperintense and heterogeneously enhance. Imaging findings are classic for polyostotic fibrous dysplasia. Fibrous dysplasia is a non-neoplastic tumor like congenital process resulting in a localized absence of osteoblast differentiation maturation with replacement of normal bone with large fibrous stroma and islets of immature woven bone. The disease occurs predominantly in children and young adults. In the polyostotic form, patients are usually diagnosed by 10 years of age. The osseous structures affected by fibrous dysplasia are weaker than normal bone is susceptible to pathologic fracture. Sarcomatous degeneration to osteosarcoma, fibrosarcoma, chondrosarcoma or malignant fibrous histiocytoma may occasionally be seen.