Bone scan (99m)Tc-MDP imaging of malignant mesothelioma with osseous differentiation.

To the Editor: Pleural malignant mesothelioma (MM) is an uncommon neoplasm with poor prognosis, strongly related to asbestos exposure, arising from mesothelial cells of the pleura. Pleurodynia is its most usual symptom, whereas the presence of pleural effusion combined with thickened pleura and calcified plaques in both computed tomographic (CT) images and respective histopathological findings set the diagnosis. Bone scan is rarely used in the diagnostic algorithm of MM. There are only two reports in the literature of incidental detection of this pathology via bone scan [1-2]. We describe an 80 years old man with history of prostate cancer, prostatectomy and past history of talc pleurodesis because of excessive pleural effusion and left pleurodynia. Past pleural effusion cytology was negative. Chest CT study revealed left pleural effusion surrounded by a thickened, calcified pleura, raising the suspicion of mesothelioma. The patient was referred to us for technetium99m (99mTc)-bone scan, which demonstrated diffuse intense uptake of 99mTc-MDP in the left hemithorax, intense in both anterior and posterior images. These findings were attributed to malignant pleural effusion, although coexistent areas of osteoblastic reaction and /or 99mTc-MDP uptake on talc deposits could not be excluded (Fig. 1). Histology after pleural biopsy and rib resection revealed MM with osseous differentiation (Fig. 2).