Desmoplastic Small Round Cell Tumor
Desmoplastic Small Round Cell Tumor in a young male who presented with abdominal pain of several months' duration. Work-up revealed a large multifocal tumor involving peritoneum and right colon. Following a colonic biopsy, he underwent hemicolectomy and omentectomy. The tumor was positive for EMA, cytokeratin AE1/AE3, desmin (perinuclear dot-like pattern), CD99 (focal positivity), NSE, and WT1. The diagnosis of desmoplastic small round cell tumor was confirmed by the presence of EWSR1-WT1 fusion transcript with RT-PCR. The image shows nests of undifferentiated small tumor cells in the lamina propria in a background of desmoplastic stroma.