Fibrous Dysplasia of the Rib Mimicking a Malignant Bone Tumor at SPECT/CT with 99mTc-MDP

We herein report a case of a 43-year-old man with a right 8th-rib bone tumor exhibiting features of malignancy at CT-scan. Considering that a SPECT/CT with 99mTc-MDP showed solitary intense radio-tracer uptake and the inconclusive results from a fine-needle biopsy, surgical en bloc tumor resection was performed. Pathologic analysis revealed a well-limited benign bone lesion ("fibrous rib dysplasia") composed by a cellular fibrous proliferation. Since benign osseous diseases may present an intense scintigraphic tracer uptake (as in this case), we suggest a certain caution when interpreting the results of SPECT/CT with 99mTc-MDP in order to avoid misdiagnosis and wrong treatments.