2024 Volume 63 Issue 4 Pages 185-193
Background : Body cavity fluid cytology is useful for diagnosing malignant mesothelioma, which can be suspected based on the cytological morphology ; however, reports on the detection of numerous psammoma bodies on cytology are limited. Herein, we report a case of epithelial pleural malignant mesothelioma, in which cytological examination revealed tumor cell clusters with numerous psammoma bodies.
Case : A man in his 60 s presented to us with computed tomographic evidence of pleural thickening 3 years 8 months after he underwent resection for a lung adenocarcinoma. A pleural fluid sample was submitted for cytology, which revealed spherical and papillary cell aggregates with numerous psammoma visualized within the agglomerates. The cells contained dense cytoplasm, and cell-within-cell arrangements with hump-like processes were observed. The tumor cells, which showed little atypia, were markedly multinucleated, with oval-shaped nuclei. The morphological characteristics were consistent with the diagnosis of malignant mesothelioma, except for the appearance of numerous psammoma bodies within the tumor clusters. Examination of cell blocks prepared from the specimens revealed positive results of the center of the psammoma bodies for the Feulgen reaction, and positive immunohistochemistry of the cells for MTAP, LCA, CD68, and αSMA, based on which they were thought to be histiocytes or myofibroblasts. Calcium was deposited around these cells.
Conclusion : This case demonstrated formation of concentric structures by psammoma bodies inflammatory cells within the mesothelioma cell clusters and also calcification within the body cavity.
