Delayed Diagnosis of Peritoneal Mesothelioma in Recurrent Ascites: A Case Report

Objective: Challenging differential diagnosis Background: Ascites is a common clinical sign noted in 3% to 4% of hospitalized medical patients. Nearly 94% of patients with ascites have non-malignant etiologies, with the most common being chronic liver disease. Peritoneal mesothelioma is an exceedingly rare malignancy associated with asbestos exposure. Here, we report the case of an elderly man who presented with recurrent loculated ascites and received a diagnosis of peritoneal mesothelioma after a delay of approximately 10 weeks. Case Report: A 67-year-old man with a history of asbestos exposure presented with abdominal distension and muscle wasting for 1 month. Initial abdominal CT was notable for smooth liver contour and massive ascites. Ascitic fluid analysis was consistent with low serum albumin-ascites gradient but showed negative cytology for malignant cells. Upper and lower endoscopies did not reveal lesions. Due to recurring ascites, serial abdominal paracenteses were performed, although cytology was negative for malignant cells. Repeat abdominal CT performed after 6 weeks showed worsening loculated ascites, with possible peritoneal carcinomatosis. At this point, percutaneous omental biopsy was performed, which established the diagnosis of peritoneal mesothelioma (75 days after initial presentation). Conclusions: In patients presenting with recurrent ascites and a history of asbestos exposure, it is important to consider the diagnosis of peritoneal mesothelioma. While 94% of patients with ascites have non-malignant etiologies, a small proportion of patients can have malignant ascites. In patients in which the first set of ascitic fluid studies are inconclusive, repeat abdominal paracentesis and omental biopsy or diagnostic laparoscopy should be expedited to avoid delays in diagnosis.