Primary peritoneal mesothelioma: A rare cause of malignant ascites

Abstract

Introduction: The evaluation of peritoneal masses requires a focused, systematic approach. While peritoneal fluid analysis and axial imaging are essential to the workup, further analysis is often needed for a final diagnosis. We present a case of primary peritoneal mesothelioma mimicking peritoneal carcinomatosis of gastrointestinal origin on computerized tomography (CT) imaging. Case presentation: A 61-year-old man presented to the hospital with an approximate 1-month history of abdominal distention, dyspnea, nausea and fatigue. Peritoneal studies revealed serum-ascites-albumin-gradient (SAAG) of lessthan 1.1, consistent with non-portal hypertension ascites. CT abdomen revealed large-volume ascites with omental caking, concerning for peritoneal carcinomatosis. Peritoneal fluid cytology was initially inconclusive, prompting ultrasound-guided peritoneal biopsies, which revealed primary abdominal mesothelioma. Conclusions: Neither CT nor peritoneal cytology are typically sufficient for the diagnosis of peritoneal mesothelioma. When strong clinical suspicion exists, early tissue biopsies should be pursued.