SMARCB1 (INI1)-deficient sinonasal carcinoma manifesting as an oral lesion: a report of 2 cases

Sinonasal carcinomas represent a rare histologically and molecularly diverse group of tumors of the head and neck cancers with an annual worldwide incidence of approximately 1 case per 100,000 inhabitants. Since the first description of a unique type of SMARCB1-deficient sinonasal carcinoma, less than 200 cases have been identified. SMARCB1-deficient sinonasal carcinomas can involve the sinonasal region with invasion into the orbits and intracranium, often leading to very poor prognosis. In view of its rarity and lack of reported case series, it is challenging to understand and characterize diagnostic features and disease behavior that could ultimately improve outcomes for these patients. Here, we present two cases of SMARCB1-deficient sinonasal carcinomas initially presenting as progressive radiolucent lesions associated with maxillary dentition and intraoral mucosal lesions. Both cases involved destruction of the left anterior maxilla that involve the maxillary sinus. The presented cases highlight a potential unknown pattern of invasion of this rare entity and poses a challenge for head and neck surgeons, dentists, and pathologists due to the potential overlapping features with odontogenic and nonodontogenic lesions. These cases highlight the importance of including SMARCB1-deficient sinonasal carcinoma in the differential diagnosis of destructive anterior maxillary entities and a multidisciplinary team for optimal diagnosis and management for such entity.