Peritoneal Multicystic Mesothelioma

**Semantic type:** Neoplastic Process

**Definition:** A mesothelial neoplasm that arises from the peritoneum and usually affects young to middle aged females. Grossly, it presents as a large multiloculated tumor mass, usually in the pelvic peritoneum. Histologically it is characterized by the presence of multiple cysts that are lined by one or more layers of mesothelial cells that do not show atypia. Patients usually present with abdominal or pelvic mass and pain. The clinical course is indolent. The tumor may reoccur, but transformation to malignant mesothelioma is rare.

**Synonyms:** - Multicystic Mesothelioma of Peritoneum - Multicystic Mesothelioma of the Peritoneum - Multilocular Peritoneal Inclusion Cyst