Sir,
A 26-year-old male patient, smoker for 10 years, presented with dyspnoea of 1 year duration. There was no history suggestive of asbestos exposure. Chest X-ray showed cardiomegaly and 2-D echocardiography showed diffuse pericardial thickening. Fine needle aspiration cytology (FNAC) from the pericardial thickening demonstrated adenocarcinoma. He was suspected to have an unknown primary malignancy with pericardial metastasis. Fluorine-18 (18F) fluoro-2-deoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) was performed to look for primary malignancy. It showed intense FDG uptake in heterogeneously enhancing soft-tissue lesion involving the entire pericardium [Figure 1]. No abnormal thickening/FDG uptake was seen in pleura. The uptake in the left supraclavicular region was an artifact due to i.v contrast. No abnormal focus of FDG uptake was seen elsewhere in the body to suggest a possible site of primary. Thus, a primary tumor of the pericardium, possibly primary malignant pericardial mesothelioma was suspected. Patient died before the confirmation of the diagnosis.
Figure 1.

Fluorine-18 FDG positron emission tomography/computed tomography images showing intense FDG uptake in heterogeneously enhancing soft tissue lesion involving the entire pericardium. No abnormal thickening/FDG uptake is seen in pleura
Primary pericardial mesotheliomas are very rare tumors constituting less than 1% of all mesotheliomas.[1,2] These tumors are known to mimic adenocarcinoma on FNAC.[3,4] Absence of abnormal uptake to suggest primary malignancy at distant site in 18F-FDG PET/CT reinforces the possibility of primary pericardial mesothelioma in these cases.
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