Human Pathology: Case Reports (Nov 2020)
SMARCB1 (INI1)-deficient sinonasal carcinoma, basaloid subtype: First reported case in Taiwan and literature review
Abstract
SMARCB1 (INI1)-deficient sinonasal carcinoma is a recently discovered poorly differentiated/undifferentiated sinonasal carcinoma characterized by complete loss of immunoexpression of SMARCB1(INI1) resulting from inactivation of SMARCB1 gene, a known tumor suppressor. Histologically, these tumors have predominant basaloid and rare rhabdoid features. Because other small blue round cell tumors of sinonasal tracts show retained SMARCB1(INI1) expression, this marker should be routinely included in immunohistochemical panels together with SMARCA4, p40, p63, p16, NUT, CD99, FLI1, CK7, CD117, and IDH1/2 as well as neuroendocrine markers to make differential diagnoses. If positive for p16, then human papillomavirus in situ hybridization is needed to exclude the possibility of HPV-related tumors. Herein, we describe the first case of SMARCB1 (INI1)-deficient sinonasal carcinoma in Taiwan. The patient, diagnosed as having stage IV disease, was treated with concurrent chemoradiotherapy and remained disease-free at two years, a better outcome than most reported cases. We review relevant literature to help physicians distinguish this tumor from other ones.
