Imaging Appearance of SMARCB1 (INI1)-Deficient Sinonasal Carcinoma: A Newly Described Sinonasal Malignancy

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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.


Figure 2 from paper
Patient 2. A, Coronal enhanced and fat-suppressed T1WI shows avid heterogeneous enhancement in right nasal cavity mass. There is no intracranial or orbital extension, and this mass was characterized as expansile. B, On this coronal STIR image, the mass is approximately isointense to cerebral cortex and can be distinguished from obstructive secretions in the adjacent ethmoid and maxillary sinuses. C, Coronal fused image from PET/CT examination demonstrates avid uptake in the right nasal cavity mass.

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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Imaging Appearance of SMARCB1 (INI1)-Deficient Sinonasal Carcinoma: A Newly Described Sinonasal Malignancy
Jeffrey Ross • Mayo Clinic, Phoenix

Dr. Jeffrey S. Ross is a Professor of Radiology at the Mayo Clinic College of Medicine, and practices neuroradiology at the Mayo Clinic in Phoenix, Arizona. His publications include over 100 peer-reviewed articles, nearly 60 non-refereed articles, 33 book chapters, and 10 books. He was an AJNR Senior Editor from 2006-2015, is a member of the editorial board for 3 other journals, and a manuscript reviewer for 10 journals. He became Editor-in-Chief of the AJNR in July 2015. He received the Gold Medal Award from the ASSR in 2013.