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SMARCA4/BRG1-Deficient Sinonasal Carcinoma
Aanchal Kakkar1, Subiyathul Farah Ashraf1, Amber Rathor1
1From the Department of Pathology (Kakkar, Ashraf, Rathor, Jain), All India Institute of Medical Sciences, New Delhi, India.
Archives of Pathology & Laboratory Medicine
|December 6, 2021
Summary
SMARCA4-deficient sinonasal carcinomas, a newly identified tumor type, exhibit aggressive behavior and resemble neuroendocrine carcinomas. Identifying these tumors aids in early diagnosis and treatment planning for better patient outcomes.
Area of Science:
- Oncology
- Pathology
- Genetics
Background:
- Molecular analysis is identifying new genetically defined sinonasal tumors.
- SMARCA4-deficient sinonasal carcinoma is a recently described entity.
- This tumor type emerged from sinonasal undifferentiated carcinoma (SNUC), neuroendocrine carcinoma (NEC), and teratocarcinosarcoma (TCS).
Purpose of the Study:
- Identify SMARCA4-deficient sinonasal carcinomas within a large institutional cohort.
- Evaluate the clinicopathologic features of these identified tumors.
Main Methods:
- SMARCA4/BRG1 immunohistochemistry on 299 poorly differentiated/undifferentiated sinonasal tumors.
- SMARCA2/BRM and INSM1 immunostaining in SMARCA4-deficient cases.
- Analysis of cytokeratin, chromogranin, synaptophysin, INSM-1, and IDH1/2 mutations.
Main Results:
- Twelve SMARCA4-deficient sinonasal carcinomas were identified.
- Morphologically, these included large cell NEC, small cell NEC, and TCS.
- SMARCA4 loss was observed, with retained SMARCA2 expression and absence of IDH1/2 mutations.
- Four of seven patients died of disease, with aggressive treatment improving outcomes.
Conclusions:
- SMARCA4-deficient sinonasal carcinomas resemble NECs and TCS, exhibiting aggressive behavior.
- Incorporating SMARCA4 immunohistochemistry aids in early recognition of these tumors.
- Further molecular analyses are needed to understand their pathogenesis.
