A 24-year-old man was noted to have a right pleural based mass on his chest radiographs. A Tc-99m HDP bone scan was ordered to evaluate the extent of the disease and to select appropriate sites of biopsy. Delayed planar and SPECT images demonstrated an area of increased uptake involving the right seventh rib lateral area. The differential diagnosis included sarcoma, lymphoma, enchondroma, fibrous dysplasia, bone cyst, or an infectious process. The patient had a biopsy-proven fibrous dysplastic lesion. Fibrous dysplasia is a benign bony neoplasm in which the osteoblasts fail to differentiate normally. Although any bone may be involved, it frequently occurs in only one bone (monostotic). Typical sites of involvement include the skull, femur, tibia, and humerus.
展开▼
