Xanthomatous pleuritis mimicking mesothelioma

Recurrent non-malignant exudative effusions remain a diagnostic and potentially management dilemma. Fluid characteristics frequently narrow the differential but fail to offer a definitive diagnosis. Medical thoracoscopy is well tolerated and allows direct visualization and biopsy of pleural processes under conscious sedation. Rarely, macroscopic appearance and even histology may be misleading. We present a case of xanthomatous pleuritis that mimicked early mesothelioma. Our patient was a 69-year-old female with a large left pleural effusion. Her medical history was significant for a recent small pericardial effusion without cardiac dysfunction. Thoracentesis revealed a non-malignant exudative effusion. Thoracoscopy demonstrated two foci of raised soft plaques with petechial hemorrhage and adhesions. Preliminary evaluation suggested chronic inflammation admixed with proliferating spindle cells and necrosis. The immunohistochemical phenotype of the spindle cells favored a spindle and epithelioid cell neoplasm, mesothelioma. Because of discord between pathologists, we repeated the thoracoscopy through the existing chest tube/thoracoscopy site. We acquired more tissue for special stains and outside review. Following extensive immunohistochemistry, the diagnosis of xanthomatous pleuritis was made. Our patient quickly recovered with steroid therapy and is without recurrence 18 months later. This case demonstrates the utility and nuances of medical thoracoscopy in a perplexing case of xanthomatous pleuritis.