Clinical, Radiological and Pathological Features of SMARCA4 / BRG1-Deficient Non-Small Cell Lung Carcinomas



Purpose: SMARCA4/BRG1-deficient non-small cell lung carcinomas (SMARCA4-dNSCLCs) are rare and malignant tumors. This study aimed to describe the clinical characteristics, computed tomography (CT) findings, and pathologic features of SMARCA4-dNSCLCs.

Methods: A total of 23 cases of SMARCA4-dNSCLCs with complete medical records, including age, course, the results of main laboratory tests, histopathology, and immunohistochemical characteristics, were retrospectively analyzed from January 2019 to August 2021.

Results: Using a combination of clinical data, CT findings, and pathological findings, SMARCA4-dNSCLCs could be more accurately diagnosed in most cases. Five patients were lost to follow-up. At the end of follow-up, 8 patients died, and the remaining patients were alive at 9–15 months. The incidence rate was similar in the right (n=11) and left (n=12) lungs. Moreover, SMARCA4-dNSCLCs were more likely to be found in the superior lobe (n=14) than in the inferior lobe (n=5) and hilum (n=4), and the median tumor size was 42.83 mm (range: 18.57-70.05 mm). Tumors showed deep, mostly inhomogeneous density with unclear margins in CT images. The lesions’ shapes included spinous protuberance (n=20), deep lobulation (n=21), and cystic component (n=13), and their radiodensity values ranged from 29.72 to 57.28 Hounsfield Units. After injection of a contrast material, heterogeneous (n=18) or homogeneous (n=2) enhancement was observed. The peak tumor enhancement was most likely to be observed in the venous phase (n=14). Pleural effusion (n=6), obstructive pneumonia (n=16), and pericardial effusion (n=5) were also detected. Twenty patients demonstrated lymph node involvement. Metastatic locations mainly included the brain (n=6), mediastinum (n=17), bone (n=10), adrenal gland (n=4), and liver (n=3). The primary tumors showed 18 F-fluorodeoxyglucose avidity in eight patients who underwent positron emission tomography-CT. All these patients showed BRG-1 deficiency but AE1/AE3, epithelial membrane antigen, and vimentin positivity. Additionally, these tumors showed different degrees of Ki-67 and programmed death-ligand 1 activities.

Conclusions: Most cases of SMARCA4-dNSCLCs in this study presented with infiltrative masses and heterogeneous densities, and their clinical outcomes were poor. Our findings highlight the importance of the differential diagnosis for SMARCA4-dNSCLCs and the utility of diagnostic imaging prior to histopathological analysis.

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