Sinonasal DEK-rearranged Papillary Non-keratinizing Squamous Cell Carcinoma: Expanding the Emerging Entity

The newly emerging sinonasal carcinomas have demonstrated diverse morphologies and specific molecular mutations along with deviant clinical behavior from conventional counterparts. Also, many sinonasal malignancies turned to be SMARCB1/SMARCA4-deficient. Even with the morphological similarities between poorly differentiated (non) keratinizing sinonasal squamous cell carcinoma (SNSCC) from DEK::AFF2 SNSCC, the two lesions are not distinguishable using the surrogate immunohistochemical marker AFF2 or molecular testing for DEK::AFF2 mutation. We report a rare case of SMARCB1-retained DEK-rearranged papillary non-keratinizing SNSCC in a 53-year-old female, who presented with a polypoid mass corresponding to the left middle turbinate. The tumor and locoregional lymph nodes were surgically resected, followed by adjuvant radiotherapy.