SMARCB1 (INI‐1) and NUT immunoexpression in a large series of head and neck carcinomas in a Brazilian reference center

Background SMARCB1 (INI‐1)‐deficient carcinomas and NUT carcinomas are aggressive neoplasms, often affecting the sinonasal region. Not uncommonly, their diagnoses are made retrospectively. Methods Through SMARCB1 (INI‐1) and NUT immunomarkers, 643 head and neck carcinomas were assessed retrospectively. Moreover, SMARCB1 (INI‐1)‐deficient and NUT carcinomas were additionally evaluated by immunohistochemistry, as well as in situ hybridization analysis for HPV and EBV. Results Four SMARCB1 (INI‐1)‐deficient carcinomas (located in lower lip, soft palate, hypopharynx and vocal cord, this latter high‐risk HPV positive) and three NUT carcinomas (all located in oropharynx) were detected, previously diagnosed as nonkeratinizing or moderately differentiated squamous cell carcinoma. All cases showed squamous differentiation. NUT carcinomas than SMARCB1 (INI‐1)‐deficient carcinomas showed low overall survival rate. Conclusion The current cases expand the clinicopathological spectrum of SMARCB1 (INI‐1)‐deficient carcinomas and NUT carcinomas. Notably, the diagnosis of these cases is easily reached through immunohistochemistry, with impact on their accurate classification, treatment, and prognosis.