Malignant pleural mesothelioma presenting as low back pain: diagnosed by bone scan coordinating with F-18 FDG PET/CT.

STUDY DESIGN: Case report.

OBJECTIVE: We report malignant pleural mesothelioma (MPM) discovered in a Tc-99m MDP bone scan as a photopenic lesion in a 64-year-old man presenting with low back pain and diagnosed with F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT).

SUMMARY OF BACKGROUND DATA: Malignant pleural mesothelioma, an uncommon neoplasm with a poor prognosis, arises from mesothelial cells of the pleura. Typically, the patient presents with either chest pain or symptoms derived from a pleural effusion such as dyspnea, or both. Most cases of MPM are initially detected on chest radiographs and primarily diagnosed with a CT scan.

METHODS: Case study with bone scan and F-18 FDG PET/CT.

RESULTS: The Tc-99m MDP bone scan showed a photopenic defect occupying the left side of the T11 vertebra and implicated the existence of a tumor. Pathologic analysis of the paraspinal tumor indicated metastatic neoplastic cells, which we initially suspected originated from the gastrointestinal tract. The CT and magnetic resonance imaging showed no additional information about the primary malignancy; therefore, we did an F-18 FDG PET/CT study, which suggested malignant pleural mesothelioma.

CONCLUSION: The present case highlights both the value of a Tc-99m MDP bone scan when MPM presents, unusually, as low back pain, and the importance of carefully interpreting bone scan images, especially for photopenic defects. It also indicates the usefulness of F-18 FDG PET/CT study in MPM in a difficult histopathological diagnosis.