A t (11; 22) (p13; q12) EWS-WT 1 positive desmoplastic small round cell tumor of the maxilla: an unusual case indicating the role of molecular diagnosis in round cell sarcomas.

A desmoplastic small round cell tumor (DSRCT) is an uncommon tumor characterized by polyphenotypic expression and a specific reciprocal translocation t (11; 22) (p13; q12). It has been rarely identified in the head and neck region. Herein, we describe a DSRCT in the maxilla of a young man, who was initially diagnosed with a primitive neuroectodermal tumor (PNET), based on histopathological appearance of a round cell tumor, with MIC2 and -FLI-1 positivity, on immunohistochemistry (IHC). Diagnosis of a DSRCT was confirmed on molecular analysis with positive -RT-PCR and sequencing results for EWS-WT1 transcript and negativity for EWS-FL1. The case is presented to highlight the value of molecular diagnosis in round cell sarcomas at uncommon sites, especially when similar IHC markers can be expressed in a PNET and a DSRCT. An exact diagnosis of a round cell sarcoma has a therapeutic relevance.