Primary splenic multicystic peritoneal mesothelioma in a young healthy male

Multicystic peritoneal mesothelioma (BMPM) is a rare, usually benign tumor that arises from peritoneal mesothelial cells that most commonly occurs in women of reproductive age. Pathogenesis of these tumors is thought to come from chronic inflammation from prior surgery, endometriosis, trauma, or recurrent peritonitis. Here we report a case of primary splenic BMPM in a 20-year-old male with no past medical or surgical history and without any typical risk factors for this condition. He underwent an open splenectomy without complication. Pathology revealed an 18 × 4 × 11 cm3 spleen with a cyst occupying 75% of the splenic surface. Sections revealed a multilocular cyst with trabeculated walls and immunohistochemical staining positive for cytokeratin (AE1/AE3) consistent with BMPM. One year post operatively he remains asymptomatic; however, his interval computed tomography (CT) scan revealed several sub centimeter nodules that either represents small splenules or neoplastic implants. These will be followed with close interval imaging.