Abstract
SMARCB1 (INI-1)-deficient sinonasal carcinoma is a newly recognized rare and aggressive subtype of sinonasal undifferentiated carcinoma and defined by the loss of nuclear SMARCB1 (INI-1) expression by immunohistochemistry. This report describes a case of SMARCB1-deficient sinonasal carcinoma in a 62-year-old male. Clinical examination revealed an expansive lesion on the left hemiface that affected the orbital cavity, paranasal region, nose, upper lip, maxilla, buccal mucosa, and oropharynx. Computed tomography confirmed an infiltrative mass of the paranasal sinus, with intraoral and orbital extension. Incisional biopsy from the mass was taken and reported as sinonasal undifferentiated carcinoma. Immunohistochemistry showed that the tumor cells were positive for AE1/AE3 and p63. Accordingly, BRD4-NUT, CD99, Chromogranin, EBV, INSM1, NKX2.2, p16, SMARCA4, S100, and Synaptophysin were all negative. INI-1 stain showed loss of expression. Unfortunately, the patient died before receiving the diagnosis of SMARCB1 (INI-1)-deficient sinonasal carcinoma. SMARCB1 (INI-1)-deficient sinonasal carcinoma is a newly recognized rare and aggressive subtype of sinonasal undifferentiated carcinoma and defined by the loss of nuclear SMARCB1 (INI-1) expression by immunohistochemistry. This report describes a case of SMARCB1-deficient sinonasal carcinoma in a 62-year-old male. Clinical examination revealed an expansive lesion on the left hemiface that affected the orbital cavity, paranasal region, nose, upper lip, maxilla, buccal mucosa, and oropharynx. Computed tomography confirmed an infiltrative mass of the paranasal sinus, with intraoral and orbital extension. Incisional biopsy from the mass was taken and reported as sinonasal undifferentiated carcinoma. Immunohistochemistry showed that the tumor cells were positive for AE1/AE3 and p63. Accordingly, BRD4-NUT, CD99, Chromogranin, EBV, INSM1, NKX2.2, p16, SMARCA4, S100, and Synaptophysin were all negative. INI-1 stain showed loss of expression. Unfortunately, the patient died before receiving the diagnosis of SMARCB1 (INI-1)-deficient sinonasal carcinoma.
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