Desmoplastic small round cell tumor of the submandibular gland--a rare but distinctive primary salivary gland neoplasm.

Desmoplastic small round cell tumor is a highly aggressive neoplasm that generally involves the peritoneum and pelvis of young patients. Only rare cases occur outside the abdomen. We report a case presenting as a primary submandibular gland tumor in a 24-year-old man. Histologically, although there were irregular tumor islands lying in an abundant desmoplastic stroma, there were also areas comprising large cellular islands with scanty stroma in between, raising the differential diagnosis of various salivary gland carcinomas. The tumor cells were medium sized, with hyperchromatic nuclei and moderate amounts of cytoplasm. The diagnosis of desmoplastic small round cell tumor was confirmed by the presence of a polyphenotypic immunoprofile (positive for cytokeratin, desmin, and neuron-specific enolase) and the characteristic EWS-WT1 gene fusion. Although rare, desmoplastic small round cell tumor has to be considered in the differential diagnosis of poorly differentiated neoplasms of the salivary gland, especially in young patients.