To the best of our knowledge, there are currently no recorded cytologic features of any effusion from rheumatoid peritonitis showing cytologic findings linked to rheumatoid pleural disease, although rheumatoid nodules have been described in the peritoneum.
A 75-year-old man with longstanding, poorly controlled rheumatoid arthritis was seen in our hospital after a motor vehicle collision. Computed tomography showed free fluid in the abdominal cavity. Laparoscopic examination revealed a large amount of nonhemorrhagic ascitic fluid and no traumatic intraabdominal injuries. Abdominal and peritoneal surfaces appeared completely normal. The ascitic fluid was aspirated through the laparoscope and sent for cytologic examination. Cytospin preparations revealed histiocytes and loosely cohesive clusters of small cytologically bland epithelioid cells amid acute inflammatory cells and granular necrotic debris. Cell block material displayed transected fibroconnective tissue fragments lined by hyperplastic mesothelium with squamous metaplasia. Immunohistochemical studies revealed that the mesothelial cells were positive for calretinin, cytokeratin 5/6, and p63.
The ascites was attributed to peritoneal disease from rheumatoid arthritis, based on the cytologic findings, immuno-profile, exclusion of other possible causes (i.e., cirrhosis, nephrotic syndrome, protein-losing enteropathy, or drugs), and patient's clinical setting.