Malignant mesothelioma cells with characteristic intracytoplasmic vacuolization and lipids.

In this brief report, we described some uncommon cytomorphological features of malignant mesothelioma (MM) cells in pleural effusions. The tumor cells exhibited abundant cytoplasmic vacuolization, with presence of single or multiple eccentric nuclei in several cells. In the Giemsa-stained smear, we observed a glossy spherical material in some cells, which tested positive in Sudan III stain. In immunocytochemical analysis, tumor cells were positive for calretinin, podoplanin, epithelial membrane antigen, and methylthioadenosine phosphorylase; tumor cells were negative for BRCA1-associated protein 1, CD68, and desmin. The intracytoplasmic vacuoles were positive for adipophilin expression.