Pleuroperitoneal Mesothelioma: A Rare Entity on 18F-FDG PET/CT.

Pleuroperitoneal mesothelioma is an extremely rare entity. Only few cases are reported worldwide. We hereby represent a case of pleural mesothelioma referred for F-18-Fluorodeoxyglucose positron emission tomography/computed tomography for response evaluation. Diffuse F-18-Fluorodeoxyglucose avid peritoneal and omental thickening noted which subsequently turned out to be mesothelial involvement on peritoneal biopsy. This case demonstrates the role of F-18-Fluorodeoxyglucose positron emission tomography/computed tomography in detecting other sites of involvement in case of malignant mesothelioma.

A 40-year-old-female without any history of occupational asbestos exposure presented with histologically proven malignant pleural mesothelioma. The patient was referred for F-18-Fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) to assess disease status following chemotherapy which revealed extensive FDG avid irregular mass like thickening involving right parietal and visceral pleura leading to collapse of the underlying lung [Figure 1]. Along with that FDG avid diffuse peritoneal and omental thickening noted [Figure 1]. Histopathological evaluation of the peritoneal biopsy confirmed presence of peritoneal mesothelioma.

Figure 1

FDG PET/CT revealed extensive FDG avid irregular mass like thickening involving right parietal and visceral pleura leading to collapse of the underlying lung (long arrows). Along with that FDG avid diffuse peritoneal and omental thickening noted (short arrows).

Malignant mesothelioma is a rare tumor that originates from the cells lining the mesothelial surfaces, including the pleura, peritoneum, pericardium, and tunica vaginalis. The most common subtype of mesothelioma is the pleural form.[1] Malignant peritoneal mesothelioma accounts for about 12.5% to 25% of malignant mesotheliomas.[2] It usually occurs in middle-aged men who commonly complain of abdominal pain or a feeling of fullness, abdominal distention or increasing abdominal girth, nausea, anorexia, and weight loss.[3] FDG PET/CT has higher sensitivity and specificity in detecting lymph node and distant metastases, thereby helpful in staging.[4] Also higher standardized uptake value in FDG PET/CT is associated with poor prognosis.[5] FDG PET/CT also has higher accuracy for treatment response evaluation in malignant mesothelioma.[6] This case further confirms the role of FDG PET/CT in detecting the extent of the disease by simultaneous detection of pleural and peritoneal lesion since conventional imaging before treatment was negative in detecting peritoneal lesions. So, 18F-FDG-PET/CT is a valuable imaging modality in the evaluation and management of malignant mesothelioma.

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