Solid-pattern desmoplastic small round cell tumor of the orbit: a case report.

Desmoplastic small round cell tumor (DSRCT) is a rare malignancy most commonly originating in the peritoneum. Only rare cases occur outside the abdomen. The present study describes a case of DSRCT in a young adolescent male who initially presented with an orbital mass. The diagnosis was confirmed by the presence of a polyphenotypic immunoprofile (positive for desmin and neural markers) and the characteristic EWS-WT1 gene fusion. Tumor histologically had an entirely solid pattern, lacking evidence of desmoplastic stroma. This purely solid variant shows that when occurring at an atypical location, DSRCT may be difficult to recognize. This reported case of DSRCT draws attention to the importance of including DSRCT in the differential diagnosis of orbital tumors.