Successful diagnosis of type II enteropathy-associated T-cell lymphoma using flow cytometry and the cell block technique of celomic fluid manifesting as massive pyoid ascites that could not be diagnosed via emergency laparotomy.

Enteropathy-associated T-cell lymphoma (EATL), an intestinal tumor of intraepithelial T lymphocytes, is a rare and highly aggressive disease. We herein describe a case of type II EATL with massive pyoid ascites in which a histological examination could not be performed despite emergency laparotomy that was successfully diagnosed using flow cytometry and the cell block technique to analyze the celomic fluid. This case suggests that EATL should be included in the differential diagnosis of pyoid ascites of unknown origin and that flow cytometry and the cell block technique of assessing celomic fluid are useful procedures for diagnosing EATL, especially in cases in which conducting a histological examination is impossible.