2023 World Conference on Lung Cancer (Posters)-EP06.05. SMARCA4/BRG1 Deficient Thoracic Neoplasms: Spectrum Encompassing Carcinomas to Undifferentiated Tumors

EP06.05. SMARCA4/BRG1 Deficient Thoracic Neoplasms: Spectrum Encompassing Carcinomas to Undifferentiated Tumors - PDF(Abstract)

Back to course

Pdf Summary

This study focuses on the evaluation of SMARCA4 deficient neoplasms in the thoracic region, including non-small cell lung carcinoma (NSCLC) and undifferentiated tumors. The aim of the study is to analyze the clinical presentation, radiological findings, morphology, and immunohistochemistry of these tumors. <br /><br />The researchers conducted a retrospective search from January 2018 to March 2023 and identified 35 cases, primarily in male patients who were chronic smokers. The primary mass was found in the lung, pleura, or mediastinum, with common sites of metastasis including lymph nodes, adrenal gland, and skeletal metastasis. <br /><br />Histopathological analysis revealed two distinct subtypes. Eighteen cases showed undifferentiated tumor cells with rhabdoid/epithelioid morphology and loss of BRG1 and BRM. These cases were positive for SOX2, showed variable staining for CK, CD34, and SALL4, and were diagnosed as thoracic SMARCA4 deficient undifferentiated tumors (TSDUT). Twelve cases exhibited features of poorly differentiated carcinoma with large polygonal cells, optically clear cytoplasm, and loss of BRG1 but with positive staining for CK, BRM, and claudin-4. These cases were diagnosed as SMARCA4 deficient non-small cell lung carcinoma (SD-NSCLC). <br /><br />Two cases showed intermediate features, resembling TSDUT but with positive expression for claudin-4 and CK. One case was diagnosed as hepatoid adenocarcinoma with dim expression of BRG1, while the second case showed loss of BRM alone but retained BRG1 expression and was diagnosed as SWI/SNF complex deficient undifferentiated tumor. <br /><br />The study concludes that morphology plays a key role in identifying subtypes of SMARCA4 deficient thoracic neoplasms and helps in performing appropriate immunohistochemistry. Loss of BRM is unique to TSDUT, while claudin-4, CD34, and SOX2 can be used as additional markers for differentiation.

Asset Subtitle

Arshi Tandon

Meta Tag

Speaker Arshi Tandon

Topic Pathology & Biomarkers

Keywords

SMARCA4 deficient neoplasms

thoracic region

non-small cell lung carcinoma

undifferentiated tumors

clinical presentation

radiological findings

morphology

immunohistochemistry

retrospective search

male patients