Abstract
We report herein on a case of malignant deciduoid mesothelioma arising in the peritoneum. A 74-year-old man was found to have ascites. Cytological examination of the ascites revealed large atypical oval cells with rich cytoplasm. The nucleus, single or multinucleated, was located at the center of the cell, and showed coarse granular chromatin and several nucleoli.
Malignant mesothelioma was suspected from these findings. From the subsequent peritoneal biopsy, the tumor was diagnosed as a malignant deciduoid mesothelioma. Immunohistochemical and electron microscopic examinations confirmed the mesothelial characteristics of the tumor cells. Cytological findings of this rare variant of a malignant mesothelioma are shown for diagnostic purposes.
