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(Slides)

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This study focuses on SMARCA4 deficient neoplasms in the thoracic region, which include non-small cell lung carcinomas (SD-NSCLC) and undifferentiated tumors (TSDUT). The aim of the study was to assess the clinical details, radiology findings, morphology, and immunohistochemistry of these tumors. A retrospective search was performed, and a total of 40 cases were identified, mostly in male patients who were smokers. The primary mass was found in the lung, pleura, or mediastinum, with metastasis detected in 37.5% of patients, most commonly in lymph nodes and skeletal sites. The study identified 21 cases of TSDUT, 14 cases of SD-NSCLC, and 5 cases with intermediate features. The survival rate was low, with only 7.5% of patients still alive, 57.5% deceased, and 35% lost to follow up. Immunohistochemistry markers were analyzed, and different patterns were observed for SD-NSCLC and TSDUT. SD-NSCLC showed a solid pattern-predominant adenocarcinoma, while TSDUT showed undifferentiated discohesive tumor cells with an admixture of rhabdoid and epitheloid cells. SMARCA4 deficiency occurs in two different phenotypic settings, with SD-NSCLC being claudin-4-positive, BRM proficient, and SOX2-negative, while TSDUT is claudin-4-negative, BRM-deficient, and SOX2-positive. The study concludes that morphology plays a key role in identifying these subtypes, and the loss of BRM is unique to TSDUT, while claudin-4, CD34, and SOX2 are other useful markers to differentiate between the two in challenging cases. This study is the largest of its kind in India and provides important insights into SMARCA4 deficient neoplasms in the thoracic region.

Asset Subtitle

Arshi Tandon

Meta Tag

Speaker Arshi Tandon

Topic Pathology & Biomarkers

Keywords

SMARCA4 deficient neoplasms

thoracic region

non-small cell lung carcinomas

undifferentiated tumors

clinical details

radiology findings

metastasis

immunohistochemistry

survival rate

phenotypic settings