SMARCB1 (INI1) is a tumor-suppressor gene that has been implicated in a growing number of malignancies involving multiple anatomic sites, including the kidneys, soft tissues, and the CNS (See OMIM *601607). The authors describe a case series of 17 patients collected from 6 different centers to give a comprehensive description of the appearance of these tumors on CT, MR, and PET/CT studies. SMARCB1 (INI1)-deficient sinonasal carcinoma should be included in the differential diagnosis of a central sinonasal mass demonstrating aggressive imaging features, particularly when there is associated calcification.
SMARCB1 (INI1)-deficient sinonasal carcinomas were first described in 2014, and this series of 17 cases represents the first imaging description. This tumor is part of a larger group of SMARCB1-deficient neoplasms, characterized by aggressive behavior and a rhabdoid cytopathologic appearance, that affect multiple anatomic sites. Clinical and imaging features overlap considerably with other aggressive sinonasal malignancies such as sinonasal undifferentiated carcinoma, which represents a common initial pathologic diagnosis in this entity. SMARCB1 (INI1)-deficient sinonasal tumors occurred most frequently in the nasoethmoidal region with invasion of the adjacent orbit and anterior cranial fossa. Avid contrast enhancement, intermediate to low T2 signal, and FDG avidity were frequent imaging features. Approximately half of the lesions demonstrated calcification, some with an unusual “hair on end” appearance, suggesting aggressive periosteal reaction.
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