In recent years, considerable progress in sinonasal tumor taxonomy has taken place with the discovery of tumor type-specific fusion oncogenes generated by chromosomal translocations (such as DEK::AFF2 and NUTM1 gene fusions), as well as recognition of inactivated tumor suppressor genes, such as SWI/SNF deficiency (detectable by immunohistochemistry), unique to specific tumor types. The gene discussed is DEK; the disease is neoplasm.