Desmoplastic Small Round Cell Tumor: RT-PCR Analysis and Immunohistochemical Detection of the Wilm's Tumor Gene WT1

Summary Desmoplastic small round cell tumor is an aggressive neoplasm first described in 1991. Recently, a reciprocal translocation t( 11 ;22)(p 13 ;q 12) has been characterized by conventional cytogenetic studies and molecular analysis. This translocation involves the Ewing’s sarco- ma gene on chromosome 22 and the Wilms’ tumor gene WT1 on chromosome 11. The chimeric transcript corre- sponding to the fusion gene could be detected by the re- verse transcriptase-polymerase chain reaction (RT- PCR). Using an anti-WTl antibody, the WT1 part of the putative chimeric protein could be recognized by im- munohistochemistry. We describe two well-character- ized cases of intraabdominal desmoplastic small round cell tumor in two male patients aged 14 and 28 with both RT-PCR analysis and immunostaining for WT1. In this report, we insist on the necessity to increase the RT- PCR analysis in DSRCT in order to obtain a precise dif- ferential diagnosis. In addition, WT1 immunostaining may serve as a useful diagnostic marker for DSRCT.