Eosinophilic ascites due to severe eosinophilic ileitis

Background: There is a broad etiology for effusion eosinophilia that includes allergic, reactive, infectious, immune, neoplastic, and idiopathic causes. We report and describe the cytomorphologic findings of a rare case of eosinophilic ascites due to severe eosinophilic ileitis. Case Presentation: A 17-year-old male manifested acutely with eosinophilic ascites due to severe biopsy-proven subserosal eosinophilic ileitis. Isolated peritoneal fluid submitted for cytologic evaluation revealed that 65% eosinophils were present in a bloody background. The patient responded to corticosteroids, with complete resolution of his ascites. Conclusion: Eosinophilic gastroenteritis with subserosal involvement should be added to the list of causes for eosinophils in peritoneal fluid. The finding of eosinophilic ascites, with appropriate clinical and laboratory findings, may warrant the need to perform laparoscopic intestinal biopsies to confirm the diagnosis.