Desmoplastic small round cell tumors of the abdomen.

Background: Desmoplastic small round cell tumors (DSRCT) have been only recently identified.

Methods: The authors report DSRCT in two pediatric patients (an 8-year-old boy and 12-year-old boy). In both patients, the initial diagnosis was rhabdomyosarcoma. The resistance to standard chemotherapy and radiation therapy prompted the authors to review the initial biopsy specimens and perform complementary immunophenotypic characterization.

Results: These analyses revealed that the tumor cells were strongly positive for keratin epithelial marker antigen, desmin, vimentin, neurospecific enolase, and S100 protein, corresponding to pleomorphic differentiation, characteristic of DSRCT:

Conclusions: The authors suggest that extensive immunohistologic characterization be performed in all cases of small round cell tumors of the abdomen so that the diagnosis of DSRCT is not overlooked. These rare tumors are refractory to chemotherapy, and initial aggressive surgery is warranted.