DESMOPLASTIC SMALL ROUND-CELL TUMORS OF THE ABDOMEN

Background. Desmoplastic small round cell tumors (DSRCT) have been onl y recently identified. Methods. The authors report DSRCT in two pediat ric patients (an 8-year-old boy and 12-year-old boy). In both patients , the initial diagnosis was rhabdomyosarcoma. The resistance to standa rd chemotherapy and radiation therapy prompted the authors to review t he initial biopsy specimens and perform complementary immunophenotypic characterization. Results. These analyses revealed that the tumor cel ls were strongly positive for keratin epithelial marker antigen, desmi n, vimentin, neurospecific enolase, and S100 protein, corresponding to pleomorphic differentiation, characteristic of DSRCT. Conclusions. Th e authors suggest that extensive immunohistologic characterization be performed in air. cases of small round cell tumors of the abdomen so t hat the diagnosis of DSRCT is not overlooked. These rare tumors are re fractory to chemotherapy, and initial aggressive surgery is warranted.