Benign multi-cystic peritoneal mesothelioma of the porta hepatis

INTRODUCTION: Our case report describes a patient where multiple laparoscopies five years from initial presentation of symptoms were performed prior to laparotomy for benign multi-cystic peritoneal mesothelioma (BMPM), which has not been documented. PRESENTATION: A 61-year-old woman presented with years of chronic abdominal pain. Computerized tomography (CT) demonstrated a multi-cystic mass near the porta hepatis, and ultrasound was concerning for contained gallbladder perforation. Fine needle aspiration (FNA) demonstrated benign ductal epithelial cells in a background of mucin and bile without the presence of malignant cells. During laparotomy, a cystic mass attached to the porta hepatis seen emanating from the small bowel mesentery, and additional small cystic lesions through the abdomen were removed. The specimen, measuring 26 × 18 × 8 cm, showed multi-loculated cysts filled with serous fluid. DISCUSSION: BMPM is a rare neoplasm of mesothelioma cells originating from serosa of viscous organs. BMPMs appear as cystic structures with thin walls containing mucinous/gelatinous fluid. Microscopic features include a lack of invasion and no increased cellularity in the stroma, with or without inflammation (Myers & Babiker, 2018). It is postulated to be either a reactive or neoplastic process. There is no gold-standard treatment for BMPM. Our case is unique in the sense that our patient required several surgical biopsies before final diagnosis could be made. CONCLUSION: This case highlights the difficulty of diagnosing BMPM and differentiating it from malignant diseases that can present similarly and can be associated with significantly worse prognosis. Defined management strategies have yet to be demonstrated.