The overwhelming majority of SMARCB1-deficient sinonasal carcinoma presents very late, with locoregionally advanced disease at diagnosis, owing to its very similar clinical presentation to other benign conditions, such as allergic rhinitis, nasal polyps, chronic sinusitis, and some commoner malignancies, such as HPV-associated squamous cell carcinoma, extranodal NK/T cells lymphoma, and mucosal melanoma. Here, SMARCB1 is linked to nasal cavity and paranasal sinus carcinoma.