title: Cytopathologic characteristics of SMARCB1 (INI-1) deficient sinonasal carcinoma: A potential diagnostic pitfall.
abstract: Tumors of the head and neck are extremely diverse and a subset are poorly differentiated and difficult to classify. Recently, a new entity has been described with rhabdoid and/or plasmacytoid cytologic features and a characteristic genetic signature-inactivation of the SMARCB1 (INI-1) tumor suppressor gene. To date, only 16 cases of SMARCB1 (INI-1) deficient sinonasal carcinoma have been described, and there are currently no reports of the cytopathologic features by fine needle aspiration (FNA) cytology. A case of a 77-year-old man who presented with a posterior ethmoid sinus lesion with invasion into the skull base and bone was reported. FNA cytology of a right retropharyngeal lymph node revealed relatively monomorphic, loosely cohesive clusters of plasmacytoid cells with occasional nucleoli, rare intranuclear cytoplasmic inclusions, and mitotic figures in a background of necrosis and absence of overt squamous or glandular differentiation. A diagnosis of metastatic myoepithelial carcinoma was made; however, retrospectively, the surgical excision showed loss of the SMARCB1 (INI-1) tumor suppressor gene by immunohistochemistry. In summary, the cytomorphologic features of SMARCB1 (INI-1) deficient sinonasal carcinoma are relatively nonspecific and overlap with other regional tumors, including myoepithelial neoplasms. As a result, this entity should be considered in the differential diagnosis for a plasmacytoid tumor arising in the sinonasal tract by FNA cytology. Diagn. Cytopathol. 2016;44:700-703. © 2016 Wiley Periodicals, Inc.
authors.affiliation: Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Derek B
authors.initials: DB
authors.lastname: Allison
authors.affiliation: Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Justin A
authors.initials: JA
authors.lastname: Bishop
authors.affiliation: Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Syed Z
authors.initials: SZ
authors.lastname: Ali
mesh_terms: D000368:Aged; D044963:Biopsy, Fine-Needle; D002277:Carcinoma / Q000235:genetics / Q000473:pathology*; D003713:Dendritic Cells / Q000473:pathology; D003937:Diagnosis, Differential; D006801:Humans; D008297:Male; D008444:Maxillary Sinus Neoplasms / Q000235:genetics / Q000473:pathology*; D009669:Nose Neoplasms / Q000235:genetics / Q000473:pathology*; D000071796:SMARCB1 Protein / Q000172:deficiency*
chemical_list: D000071796:SMARCB1 Protein; C513266:SMARCB1 protein, human
keywords: SMARCB1 (INI1); cytopathology; fine needle aspiration; sinonasal carcinoma