Multicystic peritoneal mesothelioma with floret-like multinucleated giant cells: A case report.

Multicystic peritoneal mesothelioma is an uncommon neoplasm characterized by multiple cysts adhering to the abdominal cavity. The symptoms are nonspecific, and their severity appears to be related to the size and location of the cysts. We report the case of a 55-year-old man with morbid obesity in whom a multiloculated mesenteric mass was incidentally discovered on abdominal ultrasound. Complementary imaging studies revealed a multicystic peritoneal tumour with a maximum diameter of 32cm, located in the pelvis and extending to the right hemiabdomen. Histologically, multiple cysts lined by mesothelial cells without atypia were observed, along with loose fibrous stroma containing numerous multinucleated floret-like giant cells. Based on the histopathological findings, the final diagnosis was multicystic peritoneal mesothelioma.