J Pathol Transl Med.  2022 Jan;56(1):53-56. 10.4132/jptm.2021.09.16.

TTF1-positive SMARCA4/BRG1 deficient lung adenocarcinoma

• Mehta A
• Diwan H
• Bansal D
• Gupta M

• KMID: 2524230
• DOI: http://doi.org/10.4132/jptm.2021.09.16

Abstract

SMARCA4/BRG1-deficient lung adenocarcinoma (SD-LUAD) is being recognized as a distinct subtype based on subtle differences in its clinical, morphological, and immunophenotypic attributes compared to other non–small cell lung carcinomas. We present here a case of SD-LUAD with curious thyroid transcription factor 1 (TTF1) expression in a morphologically heterogenous lung adenocarcinoma. The better differentiated area showed preservation of TTF1 expression, and a poorly differentiated tumor had loss of TTF1 expression with universal BRG1 loss.

Keyword

BRG1; Lung; Non-small cell lung carcinoma; Thyroid transcription factor 1

Figure

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  Fig. 1 Positron emission tomography computed tomography (PET-CT) image. (A) Maximum intensity projection. (B, C) Axial computed tomography. (D, E) Fused fluorodeoxyglucose PET-CT axial images showing left lung central lesion with mediastinal lymph nodes and bone lesions.

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  Fig. 2 Histopathological findings of the case. (A) Scanner view depicting two cores: one with compact morphology with a trabecular and abortive cribriform pattern (left) and another more loose and pink owing to abundant cytoplasm (right). (B) Low power view of better differentiated area (compact morphology) with tumor cells arranged in acinar and abortive cribriform pattern. (C) Tumor cells in a better differentiated area showing uniform tumor cells with scant eosinophilic cytoplasm and high nucleocytoplasmic ratio. (D) Low power view of lesser differentiated area (loose area) with tumor cells showing abundant bubbly cytoplasm, pleomorphic nuclei, and inflamed stroma. (E) Tumor cells of a lesser differentiated area showing abundant eosinophilic cytoplasm, vesicular pleomorphic nuclei, and neutrophilic emperipolesis with stroma rich in inflammatory cells.

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  Fig. 3 Representative images of immunohistochemistry. Tumor cells in a better differentiated area (A), showing cytokeratin (CK) expression in tumor cells (B), loss of BRG1 in tumor cells (C), thyroid transcription factor 1 (TTF1) expression by tumor cells in better differentiated area (D). Tumor cells in lesser differentiated area (E) showing weaker CK expression in tumor cells (F). Loss of BRG1 in tumor cells (G) and loss of TTF1 (H) in tumor cells showing poor differentiation.

Reference

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