Unusual morphology of desmoplastic small round cell tumor from an ascitic fluid in the postchemotherapy setting.

Desmoplastic small round cell tumor (DSRCT) is a malignant neoplasm that most often presents in male adolescents as an abdominal mass. Cytological features have been previously described, but only two reports noted post chemotherapy changes on effusions. We report a case of a 15-year-old male with DSRCT status postchemotherapy that presented with ascitis. Unusual morphology was seen: Numerous malignant large and single cells with prominent nucleoli and abundant cytoplasm in a background without the stroma, occasional mitosis, and the abundant apoptosis. Cell block immunocytochemistry was confirmatory. Awareness of the postchemotherapy changes in this tumor will allow us to diagnose recurrence.