RESUMO
A case of sinonasal desmoplastic small round cell tumor in a 21-year-old woman is presented. The tumor possessed the diagnostic histologic, immunohistochemical, and genetic characteristics of desmoplastic small round cell tumor. Histologically, the tumor was composed of nests of tumor cells surrounded by a desmoplastic stroma. Immunohistochemical staining was positive for keratin, vimentin, desmin, and, focally, neuron-specific enolase. The desmin immunopositivity was of a classic dot-like perinuclear pattern. RT-PCR analysis showed the fusion transcript resulting from the t(11;22)(p13;q12) reciprocal translocation. This case of sinonasal desmoplastic small round cell tumor, the third reported case not associated with a serosal surface, further obscures the nature and histogenesis of this entity.
