SMARCA4/BRG1-Deficient Non-Small Cell Lung Carcinomas: A Case Series and Review of the Literature

Metastatic INI-1-deficient undifferentiated lung cancer with EGFR 19del mutation identified in pleural effusion: a case report and review of the literature

INI-1 is a core component of the switch/sucrose-non-fermenting (SWI/SNF) complex, an ATP-dependent chromatin remodeling complex that plays a critical role in DNA repair, transcriptional regulation, and cellular differentiation. Intrathoracic tumors driven by INI-1 inactivation are exceptionally rare. This report presents the first documented case of metastatic INI-1-deficient undifferentiated lung cancer harboring a co-occurring epidermal growth factor receptor (EGFR) exon 19 deletion mutation. The clinical and pathological characteristics of the tumor are described, followed by a comprehensive review of the relevant literature.

SMARCA4-deficient non-small cell lung cancer with metastasis to the sigmoid colon: a case report

BACKGROUND

SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin, subfamily a, member 4-deficient non-small cell lung cancer (SMARCA4-dNSCLC) is a rare subtype of NSCLC whose definitive radiographic characteristics have not yet been fully delineated. Clinically, these tumors often metastasize to distant organs and lymph nodes at an early stage, which is strongly associated with poor clinical prognosis. The common metastatic sites include bone, brain, adrenal glands, liver, and spleen, whereas intestinal metastasis is extremely rare. In this case, we describe a rare instance of SMARCA4-deficient NSCLC with metastasis to the sigmoid colon.

CASE DESCRIPTION

A 59-year-old male presented with hoarseness and shortness of breath. Computed tomography (CT) imaging revealed an irregular mass in the posterior apical segment of the upper lobe of the left lung, with enlarged lymph nodes in the mediastinum and left lung hilum. A biopsy of the lung mass confirmed the diagnosis of NSCLC with SMARCA4 gene deletion. CT also revealed uneven thickening of the sigmoid colon wall, which was proved to be metastases from the lung cancer through surgical pathology. The patient initially underwent chemotherapy combined with immunotherapy and intensity-modulated radiotherapy for the lungs. However, a follow-up CT revealed progression in the sigmoid colon tumor. Consequently, the patient underwent laparoscopic radical sigmoid colectomy with regional lymph node dissection. Two months postoperatively, metastasis to the left adrenal gland was detected. The treatment regimen was adjusted to a combination therapy consisting of gemcitabine, nedaplatin, bevacizumab, and camrelizumab accordingly. The patient demonstrated a favorable response to this treatment, with no evidence of recurrence or further metastasis to date.

CONCLUSIONS

This case represents the first reported instance of SMARCA4-dNSCLC with metastasis to the sigmoid colon. The atypical clinical and radiological features of this condition pose significant diagnostic challenges, particularly in differentiating metastatic lesions from primary colonic tumors. This case underscores the significance of recognizing rare metastatic patterns in SMARCA4-dNSCLC, enriching the literature on its diverse manifestations and providing a critical reference for clinicians in diagnosing and managing SMARCA4-dNSCLC with sigmoid colon metastasis.

The impact of SMARCA4 loss in non-small cell lung cancer therapy

This case report explores the therapeutic impact of SMARCA4 loss in a 63-year-old female patient with a history of smoking, hypertension, hypercholesterolemia, and prior surgeries for breast and pancreatic carcinomas, who presented with a new pulmonary nodule. On February 23, 2024, a CT scan identified a solid pulmonary nodule in the right lower lobe. A PET scan confirmed the nodule's metabolic activity. By May 8, 2024, follow-up imaging revealed disease progression and central cavitation in the nodule. Following admission on June 14, 2024, the patient underwent a multidisciplinary evaluation, and a lobectomy of the right lower lobe was performed. Pre-operative assessments indicated good general health and no respiratory distress. Post-surgical histology demonstrated a SMARCA4-deficient non-small cell lung cancer with loss of Brahma-related gene 1. Immunohistochemical analyses showed positive expressions of Cytokeratin-7, focal cytoplasmic positivity for Hepar-1 and loss of BRG-1. The surgery successfully removed the neoplasm, and the patient remained alive and disease-free post-operation. The follow-up plan includes tri-annual visits with contrast-enhanced chest and abdomen CT scans to monitor for recurrence. The case underscores the significance of identifying SMARCA4 deficiencies in NSCLC and advocating for tailored therapeutic strategies. Enhanced awareness and understanding of SMARCA4-deficient NSCLC can guide future treatment protocols and improve patient outcomes.

A case report of SMARCA4-deficient gastric cancer and review of the literature

We report the case of a 50-year-old female with gastric carcinoma. The tumor was positive for epithelial and other immunological markers; however, SMARCA4 was completely inactivated. The histological and immunophenotypic findings were consistent with a diagnosis of SMARCA4-DTS. Next-generation sequencing identified a frameshift mutation in SMARCA4. The pathological diagnosis was SMARCA4-deficient gastric carcinoma. The tumor exhibits a poor response to conventional chemotherapy and has a poor prognosis; therefore, correct diagnosis is necessary. Moreover, new therapies such as EZH2 inhibitors and etoposide should be considered in cases where conventional chemotherapy is ineffective.

Concurrent EGFR mutation and SMARCA4 deficiency in non-small cell lung cancer: A case report and literature review

RATIONALE

SMARCA4-deficient non-small cell lung cancer (NSCLC) represents a highly aggressive subtype with poor prognosis. While clinical studies have identified common co-mutations in TP53, LRP1B, STK11, KEAP1, and KRAS, actionable driver mutations such as EGFR or ALK are rarely reported in conjunction with SMARCA4 deficiency. This case presents a rare instance of NSCLC featuring both an EGFR exon 21 L858R mutation and SMARCA4 deficiency, highlighting the challenges in treatment and the need for novel therapeutic strategies.

PATIENT CONCERNS

A 79-year-old female patient presented with concerns of a lung mass, suspected to be peripheral lung cancer based on diagnostic imaging.

DIAGNOSES

Histopathological evaluation confirmed SMARCA4-deficient NSCLC. Molecular genetic analysis further revealed an EGFR exon 21 L858R mutation.

INTERVENTIONS

The patient was initially treated with osimertinib, an EGFR tyrosine kinase inhibitor. Upon disease progression, treatment was adjusted to include anlotinib in combination with ongoing osimertinib.

OUTCOMES

The initial treatment with osimertinib led to partial remission. However, disease progression necessitated a change in therapy. The combination treatment stabilized the disease temporarily, achieving a stable disease status.

LESSONS

This case underscores the transient efficacy of targeted therapy in SMARCA4-deficient NSCLC with concurrent EGFR mutations. It highlights the need for continuous therapeutic adjustments and emphasizes the importance of further research into effective strategies for treating this complex and challenging subset of NSCLC, as current modalities have limitations in sustained efficacy.

SMARCA4-deficient undifferentiated tumor with high quality of life and far exceeding predicted survival: A case report

RATIONALE

SMARCA4-deficient undifferentiated tumor (SMARCA4-UT) is a recently reported rare malignancy that can rapidly metastasize to tissues and organs throughout the body. The tumor is characterized by a lower response to platinum-based chemotherapy. More regrettably, the mean survival time of patients with this disease after diagnosis is only 4 to 7 months.

PATIENT CONCERNS

A 58-year-old man was admitted to a hospital for fatigue, sudden syncope, and a mass-like shadow of his left upper lobe demonstrated by a pulmonary computed tomographic. Based on his subsequent clinical and pathological features, he was highly suspected of SMARCA4-UT.

DIAGNOSES

Combined with next-generation sequencing genetic testing and immunohistochemical examination results, the patient was diagnosed with SMARCA4-UT.

INTERVENTIONS

The patient received a left upper lobectomy and lymph node dissection, four-course chemotherapy divided into 8 sessions with the use of paclitaxel simply, and a proper post-discharge self-care.

OUTCOMES

The patient's operation and chemotherapy were all successful and he maintained a high quality of life after surgery that far exceeded his predicted survival.

LESSONS

Early diagnosis, higher education level, attention to the disease and complications, reducing chemotherapy damage, adequate nutrient intake, relieving symptoms, controlling depression, and maintaining immunity and the ability to perform activities of daily living may all be the positive factors that can prolong the survival of patients with SMARCA4-UT.

SMARCA4‑deficient uterine adnexal tumor with ascites: A case report and literature review

SWI/SNF-related matrix-associated actin-dependent regulator of chromatin subfamily A member 4 (SMARCA4)-deficient tumors are rare and highly aggressive tumors characterized by a loss of SMARCA4 expression, and SMARCA4-deficient tumors in the adnexal area of the uterus are particularly rare. The present study describes the case of a 64-year-old woman who was admitted to Weifang People's Hospital (Weifang, China) with abdominal distension, and was observed to have a mass with ascites in the adnexal area of the uterus. Based on clinical, imaging and pathological findings, the patient was diagnosed with a SMARCA4-deficient adnexal tumor with ascites. Biopsy of the left and right adnexal lesions was performed, and the patient was administered chemotherapy. After one cycle of bevacizumab, sindilizumab and carboplatin, no further treatment was administered. After biopsy and chemotherapy, the abdominal distension was alleviated and the general condition of the patient was satisfactory. The patient was followed up and died 3 months after treatment. Notably, it is important to avoid misdiagnosing this tumor as other types of adnexal uterine tumors, and morphological and immunohistochemical features may be useful for diagnosing primary SMARCA4-deficient tumors in the adnexal area of the uterus.

BET Bromodomain Inhibition Potentiates Ocular Melanoma Therapy by Inducing Cell Cycle Arrest

Purpose

Ocular melanoma is a common primary malignant ocular tumor in adults with limited effective treatments. Epigenetic regulation plays an important role in tumor development. The switching/sucrose nonfermentation (SWI/SNF) chromatin remodeling complex and bromodomain and extraterminal domain family proteins are epigenetic regulators involved in several cancers. We aimed to screen a candidate small molecule inhibitor targeting these regulators and investigate its effect and mechanism in ocular melanoma.

Methods

We observed phenotypes caused by knockdown of the corresponding gene and synergistic effects with BRD inhibitor treatment and SWI/SNF complex knockdown. The effect of JQ-1 on ocular melanoma cell cycle and apoptosis was analyzed with flow cytometry. Via RNA sequencing, we also explored the mechanism of BRD4.

Results

The best tumor inhibitory effect was observed for the BRD4 inhibitor (JQ-1), although there were no statistically obvious changes in the shBRD4 and shBRD9 groups. Interestingly, the inhibitory effect of JQ-1 was decrease in the shBRD4 group. JQ-1 inhibits the growth of melanoma in various cell lines and in tumor-bearing mice. We found 17 of these 28 common differentially expressed genes were downregulated after MEL270 and MEL290 cells treated with JQ-1. Four of these 17 genes, TP53I11, SH2D5, SEMA5A, and MDGA1, were positively correlated with BRD4. In TCGA database, low expression of TP53I11, SH2D5, SEMA5A, and MDGA1 improved the overall survival rate of patients. Furthermore, the disease-free survival rate was increased in the groups with low expression of TP53I11, SH2D5, and SEMA5A.

Conclusions

JQ-1 may act downstream of BRD4 and suppress ocular melanoma growth by inducing G1 cell cycle arrest.

A case of surgically treated non-metastatic SMARCA4-deficient undifferentiated thoracic tumor: a case report and literature review

SMARCA4-deficient undifferentiated thoracic tumor (SMARCA4-UT) is a rare malignant tumor characterized by inactivation of the SMARCA4 gene and the presence of undifferentiated or rhabdoid morphology in the tissue. This tumor is highly invasive, typically diagnosed at advanced stages III or IV, and commonly involves thoracic structures, such as the mediastinum and chest wall. Reported cases are limited and treatment guidelines have not yet been established. Here, we present a rare case of surgically treated non-metastatic SMARCA4-UT. The patient presented with blood-tinged sputum, dyspnea, and a history of heavy smoking, and underwent surgery after preoperative evaluation ruled out contraindications. The tumor was successfully removed along with the relevant lymph nodes; analysis determined it to be stage IIB T3N0M0. No recurrence was detected at two months post-surgery. However, four months after surgery, the tumor recurred and invaded the adjacent ribs. The diagnosis, differential diagnosis, and treatment of SMARCA4-deficient undifferentiated lung tumors is considered. The combination of chemotherapy and immunotherapy has shown efficacy, and other treatments such as anti-angiogenic drugs, histone deacetylase inhibitors (HDACi), enhancer of zeste 2 polycomb repressive complex 2 subunit (EZH2) inhibitors, and oxidative phosphorylation (OXPHOS) inhibitors may also be beneficial in treating SMARCA4-UT.

SMARCA4 deficiency and mutations are frequent in large cell lung carcinoma and are prognostically significant

SMARCA4 mutation has emerged as a marker of poor prognosis in lung cancer and has potential predictive value in cancer treatment, but recommendations for which patients require its investigation are lacking. We comprehensively studied SMARCA4 alterations and the clinicopathological significance in a large cohort of immunohistochemically-subtyped non-small cell lung cancer (NSCLC). A total of 1416 patients was studied for the presence of SMARCA4 deficiency by immunohistochemistry (IHC). Thereafter, comprehensive sequencing of tumours was performed for 397 of these patients to study the mutational spectrum of SWI/SNF and SMARCA4 aberrations. IHC evidence of SMARCA4 deficiency was found in 2.9% of NSCLC. Of the sequenced tumours, 38.3% showed aberration in SWI/SNF complex, and 9.3% had SMARCA4 mutations. Strikingly, SMARCA4 aberrations were much more prevalent in large cell carcinoma (LCC) than other histological tumour subtypes. SMARCA4-deficient and SMARCA4-mutated tumours accounted for 40.5% and 51.4% of all LCC, respectively. Multivariable analyses confirmed SMARCA4 mutation was an independent prognostic factor in lung cancer. The immunophenotype of a subset of these tumours frequently showed TTF1 negativity and HepPAR1 positivity. SMARCA4 mutation or its deficiency was associated with positive smoking history and poor prognosis. It also demonstrated mutual exclusion with EGFR mutation. Taken together, the high incidence of SMARCA4 aberrations in LCC may indicate its diagnostic and prognostic value. Our study established the necessity of SMARCA4 IHC in the identification of SMARCA4-aberrant tumours, and this may be of particular importance in LCC and tumours without known driver events.

Rare SMARCA4-deficient thoracic tumor: Insights into molecular characterization and optimal therapeutics methods

INTRODUCTIONS

The 2021 WHO Classification of Thoracic Tumors recognized SMARCA4-deficient undifferentiated thoracic tumors (SMARCA4-dUT) as a distinct entity that shows a striking overlap in demographic and molecular profiles with SMARCA4-deficient non-small lung cancer (SMARCA4-dNSCLC). The implications of SMARCA4 deficiency based on immunohistochemistry remain unclear. We aimed to investigate molecular characteristics of SMARCA4-deficient thoracic tumors (SDTT) and explore optimal therapeutics.

METHODS

From June.15, 2018, to Nov.15, 2023, a large cohort including patients diagnosed with SMARCA4-deficient (N = 196) and SMARCA4-intact (N = 438) thoracic tumors confirmed by immunohistochemistry at SYSUCC were screened. Clinicopathologic and molecular characteristics were identified and compared. External SRRSH cohort (N = 34) was combined into a pooled cohort to compare clinical outcome of first-line therapy efficacy.

RESULTS

SDTT is male predominance with smoking history, high tumor burden, and adrenal metastases. The relationship between SMARCA4 mutation and protein expression is not completely parallel. The majority of SMARCA4-deficient patients harbor truncating (Class-I) SMARCA4 mutations, whereas class-II alterations and wild-type also exist. Compared with SMARCA4-intact thoracic tumors, patients with SDTT displayed a higher tumor mutation burden (TMB) and associated with a shorter median OS (16.8 months vs. Not reached; P < 0.001). Notably, SMARCA4 protein deficiency, rather than genetic mutations, played a decisive role in these differences. SDTT is generally resistant to chemotherapy, while sensitive to chemoimmunotherapy (median PFS: 7.5 vs. 3.5 months, P < 0.001). In particular, patients with SMARCA4 deficient thoracic tumors treated with paclitaxel-based chemoimmunotherapy achieved a longer median PFS than those with pemetrexed-based chemoimmunotherapy (10.0 vs. 7.3 months, P = 0.028).

CONCLUSIONS

SMARCA4 protein deficiency, rather than genetic mutations, played a decisive role in its characteristics of higher TMB and poor prognosis. Chemoimmunotherapy serves as the optimal option in the current treatment regimen. Paclitaxel-based chemoimmunotherapy performed better than those with pemetrexed-based chemoimmunotherapy.

Effectiveness of Immunotherapy in Non-Small Cell Lung Cancer Patients with a Diagnosis of COPD: Is This a Hidden Prognosticator for Survival and a Risk Factor for Immune-Related Adverse Events?

The interplay between the immune system and chronic obstructive pulmonary disease (COPD) and non-small cell lung cancer (NSCLC) is complex and multifaceted. In COPD, chronic inflammation and oxidative stress can lead to immune dysfunction that can exacerbate lung damage, further worsening the respiratory symptoms. In NSCLC, immune cells can recognise and attack the cancer cells, which, however, can evade or suppress the immune response by various mechanisms, such as expressing immune checkpoint proteins or secreting immunosuppressive cytokines, thus creating an immunosuppressive tumour microenvironment that promotes cancer progression and metastasis. The interaction between COPD and NSCLC further complicates the immune response. In patients with both diseases, COPD can impair the immune response against cancer cells by reducing or suppressing the activity of immune cells, or altering their cytokine profile. Moreover, anti-cancer treatments can also affect the immune system and worsen COPD symptoms by causing lung inflammation and fibrosis. Immunotherapy itself can also cause immune-related adverse events that could worsen the respiratory symptoms in patients with COPD-compromised lungs. In the present review, we tried to understand the interplay between the two pathologies and how the efficacy of immunotherapy in NSCLC patients with COPD is affected in these patients.

Clinicopathological characteristics and treatment outcomes of advanced SMARCA4-deficient thoracic tumors

PURPOSE

SMARCA4-deficient thoracic tumors, characterized by distinct clinicopathological, morphological, immunohistochemical, and genetic features, differ significantly from conventional non-small-cell lung carcinomas (NSCLCs). This group encompasses both SMARCA4-deficient NSCLCs (SMARCA4-NSCLCs) and SMARCA4-deficient undifferentiated tumors (SMARCA4-UTs). The efficacy of PD-1 inhibitors in treating SMARCA4-deficient thoracic tumors remains uncertain.

METHODS

Medical records of 36 patients diagnosed with stage IIIB, IIIC, or IV SMARCA4-deficient thoracic tumors were analyzed. We assessed the clinical, pathological, and genetic features of these patients through immunohistochemistry (IHC) and a 68-gene panel next-generation sequencing (NGS). We compared the differences between SMARCA4-NSCLCs and SMARCA4-UTs, and evaluated the impact of chemotherapy and immunotherapy on patient outcomes.

RESULTS

The majority of patients with SMARCA4-deficient thoracic tumors were heavy-smoking males, averaging 64.6 years in age. IHC predominantly showed weak or negative staining for markers such as TTF-1, CK5/6, p40, synaptophysin, chromogranin A, and CD56, which are often associated with adenocarcinoma, squamous cell carcinoma, and neuroendocrine tumors. The most common genetic mutations identified via NGS included TP53, CDKN2A, KRAS, STK11, NF1, and PTEN. No significant overall survival (OS) difference was observed between SMARCA4-NSCLCs and SMARCA4-UTs (p = 0.366). The median OS for patients treated with chemotherapy (n = 9) was 447 days, while the median OS for patients undergoing PD-1-inhibitor-based therapy (n = 16) was not reached (p = 0.105).

CONCLUSION

SMARCA4-deficient thoracic tumors exhibit distinct characteristics from conventional NSCLCs, and PD-1 inhibitors show promise in treating advanced SMARCA4-deficient thoracic tumors.

SMARCA4‑deficient non‑small cell lung cancer with an EGFR mutation: A case report

SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin, subfamily a, member 4 (SMARCA4)-deficient non-small cell lung cancer (dNSCLC) is a rare malignant tumor that originates in the lungs. It occurs more frequently in male smokers, and the epidermal growth factor receptor (EGFR) gene is often mutation-free. In the present study, the case of a 60-year-old, non-smoking female patient diagnosed with SMARCA4-dNSCLC is reported. Biopsy of the tumor showed solid flaky, nest-like infiltrating growth. Immunohistochemistry revealed the following: SMARCA4/BRG1(-), SMARCB1/INI-1(+), cytokeratin7 (+), cytokeratin 5.2 (+), CK5/6(+) and calretinin(+). The Ki-67 positivity index was 75%, and the thyroid transcription factor-1, NapsinA, p40, nuclear protein in testis, CD34, Sal-like protein 4, SRY-box transcription factor 2 and synaptophysin were negative. Molecular analysis showed mutations in both EGFR and TP53. The pathological diagnosis was SMARCA4-dNSCLC with an EGFR gene mutation. The present case report could be used for broadening the pathological diagnosis of SMARCA4-dNSCLC and for selecting appropriate treatment approaches.

Diagnosis and management of gastrointestinal SMARCA4-deficient undifferentiated tumors

SMARCA4-deficient undifferentiated tumors are a rare clinical entity with an aggressive clinical course, poor prognosis, and no standard-of-care therapeutic approach. These have most frequently been documented in the lung and thoracic cavity. There is a growing body of evidence for the role of immunotherapy in SMARCA4-deficient lung cancer, a disease process that historically does very poorly with cytotoxic chemotherapy alone. We present three cases where the primary tumors were instead found within the gastrointestinal system: two originating from the small bowel and one from the esophagus. In all three cases, clinical response was seen with pembrolizumab therapy, with two of the three patients receiving long-term benefit. Our series suggests that anti-PD1 immunotherapy may have promising efficacy for undifferentiated carcinomas of the gastrointestinal tract with SMARCA4 deficiency.

The clinicopathological features of BRG1-deficient non-small cell lung cancer and its response to immunotherapy: A single-center retrospective study

PURPOSE

BRG1-deficient NSCLCs have been more intriguing recently for its highly aggressive clinical behavior and no effective therapies. This study characterized the clinical and pathological features of BRG1-deficient NSCLCs and investigated their response to immunotherapy.

METHODS

Forty-seven cases with BRG1-deficient NSCLC were included. Immunohistochemical markers such as BRG1, CK7, TTF-1, NapsinA, P40, HepPar-1, Ki-67, BRM, ARID1A and ARID1B were stained. Additionally, the PD-L1 expression level, overall survival, progression-free survival and disease control rate of patients received immunotherapy were evaluated.

RESULTS

This study revealed that: (1) Patients with BRG1-deficient NSCLC have a male predominance (89.4 %), smoker enrichment (76.6 %) and poor prognosis (median OS: 7.0 months for advanced stage). (2) Histologically, BRG1-deficient NSCLCs presented significant morphological diversity and no lepidic pattern. Inflammatory infiltration and tumor necrosis was a prominent feature. Immunohistochemical analyses showed a distinctive uniform immunophenotype (TTF-1-/NapsinA-/CK7+) in 60.9 % (28/46) of cases and HepPar-1 positive in 46.5 % (20/43) of cases. BRM loss or significant reduction coexisted in 11.8 % (4/34) of cases. No case (0/37) showed loss of ARID1A or ARID1B. (3) Eight patients with advanced tumor stage had received immunotherapy and 4 cases achieved a sustainable clinical response with the disease control rate of 50 %.

CONCLUSION

BRG1-deficient NSCLC showed diverse histopathological patterns and a unique immunohistochemical phenotype. ICIs-based immunotherapy is a promising therapy needs to be investigated further for BRG1- deficient NSCLC.

Molecular, clinicopathological characteristics and surgical results of resectable SMARCA4-deficient thoracic tumors

PURPOSE

SMARCA4-deficient thoracic tumors are rapid aggressive malignancies, often diagnosed at an advanced and inoperable stage. The value of pulmonary resection for resectable SMARCA4-deficient thoracic tumors is largely unknown.

METHODS

In this observational study, we included 45 patients who received surgery for stage I-III SMARCA4-deficient tumors. We compared the molecular, clinicopathological characteristics and survival between SMARCA4-dNSCLC and SMARCA4-deficient undifferentiated tumor (SMARCA4-dUT) patients.

RESULTS

Thirty-four SMARCA4-dNSCLC and 11 SMARCA4-dUT patients were included in this study. Molecular profiles were available in 33 out of 45 patients. The most common mutated gene was TP53 (21, 64%), and followed by STK11 (9, 27%), KRAS (5, 15%), FGFR1 (4, 12%) and ROS1 (4, 12%). There were 3 patients that harbored ALK mutation including 1 EML4-ALK rearrangement. There were 2 patients that harbored EGFR rare site missense mutation. SMARCA4-dUT patients had significance worse TTP (HR = 4.35 95% CI 1.77-10.71, p = 0.001) and OS (HR = 4.27, 95% CI 1.12-16.35, p = 0.022) compared to SMARCA4-dNSCLC patients. SMARCA4-dUT histologic type, stage II/III, R1/2 resection and lymphovascular invasion were independent poor prognostic predictors for both TTP and OS. There were 8 patients who received immunotherapy, the objective response rate was 50%. The SMARCA4-dNSCLC patient with ALK rearrangement was treated with crizotinib as second-line therapy, and achieved stable disease for 9.7 months.

CONCLUSION

Patients with SMARCA4-deficient tumors have a high probability of early recurrence after surgery, except for stage I patients. Immunotherapy seems to be a valuable strategy to treat recurrence.

Validation of a Transcriptome-Based Assay for Classifying Cancers of Unknown Primary Origin

INTRODUCTION

Cancers assume a variety of distinct histologies, and may originate from a myriad of sites including solid organs, hematopoietic cells, and connective tissue. Clinical decision-making based on consensus guidelines such as the National Comprehensive Cancer Network (NCCN) is often predicated on a specific histologic and anatomic diagnosis, supported by clinical features and pathologist interpretation of morphology and immunohistochemical (IHC) staining patterns. However, in patients with nonspecific morphologic and IHC findings-in addition to ambiguous clinical presentations such as recurrence versus new primary-a definitive diagnosis may not be possible, resulting in the patient being categorized as having a cancer of unknown primary (CUP). Therapeutic options and clinical outcomes are poor for patients with CUP, with a median survival of 8-11 months.

METHODS

Here, we describe and validate the Tempus Tumor Origin (Tempus TO) assay, an RNA-sequencing-based machine learning classifier capable of discriminating between 68 clinically relevant cancer subtypes. Model accuracy was assessed using primary and/or metastatic samples with known subtype.

RESULTS

We show that the Tempus TO model is 91% accurate when assessed on both a retrospectively held out cohort and a set of samples sequenced after model freeze that collectively contained 9210 total samples with known diagnoses. When evaluated on a cohort of CUPs, the model recapitulated established associations between genomic alterations and cancer subtype.

DISCUSSION

Combining diagnostic prediction tests (e.g., Tempus TO) with sequencing-based variant reporting (e.g., Tempus xT) may expand therapeutic options for patients with cancers of unknown primary or uncertain histology.

Dynamic and Static 18F-FDG PET/CT Imaging in SMARCA4-Deficient Non-Small Cell Lung Cancer and Response to Therapy: A Case Report

SMARCA4-deficient non-small cell lung cancer (NSCLC) is a more recently recognized subset of NSCLC. We describe the ¹⁸F-fluorodeoxyglucose (FDG) PET/CT findings in a rare case of SMARCA4-deficient NSCLC and response to therapy. A 45-year-old male patient with a history of heavy smoking (10 years) underwent an ¹⁸F-fluorodeoxyglucose (FDG) PET/CT dynamic (chest) + static (whole-body) scan for diagnosis and pre-treatment staging. ¹⁸F-FDG PET/CT showed an FDG-avid mass in the upper lobe of the left lung (SUV_max of 22.4) and FDG-avid lymph nodes (LN) in the left pulmonary hilar region (SUV_max of 5.7). In addition, there were multiple metastases throughout the body, including in the distant LNs, adrenal glands, bone, left subcutaneous lumbar region, and brain. Pathological findings confirmed SMARCA4-deficient NSCLC. After four cycles of chemotherapy and immune checkpoint inhibitors (ICI), the patient underwent again an ¹⁸F-FDG PET/CT scan (including a dynamic scan) for efficacy evaluation. We report a case that deepens the understanding of the ¹⁸F-FDG PET/CT presentation of SMARCA4-deficient NSCLC as well as dynamic imaging features and parametric characteristics.

SMARCA4 as a support for the differential diagnosis of poorly differentiated lung carcinomas

Among non-small cell lung cancers (NSCLCs), sarcomatoid carcinomas account for 3%. They are rare tumours with a poor prognosis, classified into three subgroups, namely pleomorphic carcinoma, pulmonary blastoma and carcinosarcoma. In the 5th edition of WHO Classification of Thoracic Tumours more space is given to SMARC4-deficient lung cancers. Although studies on SMARCA4-deficient lung tumours are limited, a small percentage of SMARCA4 loss is present within NSCLCs. This finding is clinically relevant, as the loss of the SMARCA4 gene is associated with a worse prognosis. In our study, we analysed the presence of the main catalytic subunit of the SMARCA4 gene, the BRG1 protein, in 60 sarcomatoid lung tumours. The results of our study show that 5.3% of sarcomatoid carcinomas have BRG1-loss in tumour cells, proving that a non-negligible amount of lung sarcomatoid carcinomas are SMARCA4-deficient. These data open the debate on the necessity of including the detection of SMARCA4 within a standardised immunohistochemical panel.

Clinical characteristics and prognostic analysis of SMARCA4-deficient non-small cell lung cancer

PURPOSE

To improve the understanding of special types of tumors, we summarized and analyzed the clinicopathological features and prognostic factors of SMARCA4-deficient non-small cell lung cancer (SMARCA4-dNSCLC).

METHODS

We selected 105 patients with SMARCA4-dNSCLC and 221 patients with SMARCA4-intact non-small cell lung cancer (SMARCA4-iNSCLC) by performing immunohistochemical analysis of 1520 NSCLC samples, and we assessed the patients' clinicopathological features and survival state.

RESULTS

(1) SMARCA4-dNSCLC was significantly associated with older age, male sex, smoking history, larger invasive tumor size, higher tumor proliferation index (Ki-67), more adrenal metastases, more lymph node metastases, and few EGFR mutations (p < 0.05). The tumors were mostly negative for thyroid transcription factor-1 (TTF-1), CD34, and p40 and positive for cytokeratin 7 (CK7) in immunohistochemistry (IHC). Nineteen SMARCA4-dNSCLC patients mostly had TP53, SMARCA4, and LRP1B mutations, and 48% of them had SMARCA4 frameshift mutations. SMARCA4-dNSCLC patients have a worse prognosis than SMARCA4-iNSCLC patients (HR: 0.27; 95% CI: 0.17-0.45). The overall survival (OS) of patients with stage III SMARCA4-dNSCLC was worse than that of patients with SMARCA4-iNSCLC, and the OS of stage IV SMARCA4-dNSCLC patients was also worse than that of SMARCA4-iNSCLC patients (p < 0.01). (2) Multivariate regression analysis showed that sex (HR: 4.12; 95% CI: 1.03-16.39) and smoking history (HR: 2.29; 95% CI: 1.04-5.02) had significant effects on the survival time of SMARCA4-dNSCLC patients. In SMARCA4-dNSCLC patients without distant metastases (stage I-III), patients with stage N2 or N3 lymph node metastases (HR: 6.35; 95% CI: 1.07-37.47) had a poor prognosis. Among patients with SMARCA4-dNSCLC who were treated and had distant metastases (stage IV), male patients and patients treated with immunotherapy combined with chemotherapy showed a longer median overall survival (mOS).

CONCLUSION

SMARCA4-dNSCLC has unique clinicopathological features and a shorter survival prognosis than SMARCA4-iNSCLC. The efficacy of immunotherapy combined with chemotherapy needs to be observed for longer periods.

SMARCA4-deficient undifferentiated thoracic tumor: A case report

BACKGROUND

SMARCA4-deficient undifferentiated tumors (SMARCA4-DUTs) present with diverse clinical manifestations and progress to metastasis and even cause death within a few months. This novel subset of undifferentiated tumors occurs in the middle-aged population and is strongly associated with a smoking history. Distinguishing it from other malignancies is challenging.

CASE SUMMARY

A 62-year-old man presented with chest pain for 7 d. The patient had no respiratory symptoms and normal pulmonary function test results. The patient had been a smoker for 8 years and quit smoking 2 years ago. Chest computed tomography revealed a huge mass involving the left upper and lower lung lobes with pericardial invasion and multiple metastases. Tumor samples were obtained using open frozen biopsy, after several unsuccessful attempts. The tumor was composed of sheets of undifferentiated disclosive cells with vesicular nuclei and prominent nucleoli. The differential diagnosis included high-grade lymphoma, germ cell tumor, NUT carcinoma, undifferentiated carcinoma, and sarcoma. The tumor cells were large, arranged in sheets, and did not exhibit glandular or squamous differentiation. Frequent foci of necrosis were noted. There was no evidence of epithelial differentiation on immunohistochemical staining. The SMARCA4 stain showed complete loss of expression of SMARCA4, which is diagnostic.

CONCLUSION

In the present case, thoracic SMARCA4-DUT was diagnosed based on clinical features, absence of epithelial differentiation, and negative SMARCA4 expression.

Case report: Heterogenous SMARCA4-deficient thoracic non-small cell lung carcinoma with various responses to nivolumab

SMARCA4-deficient non-small cell carcinoma is an aggressive neoplasm with poor outcome. Several studies have highlighted its immunochemistry, pathophysiology, and underlying mechanisms, but studies of its definite treatment are few. Here, we report on a 69-year-old male with heterogenous pathological presentations of SMARCA4-deficient non-small cell carcinoma. He initially presented with neck lymphadenopathies. Immunohistochemistry staining and genomic profiling confirmed the diagnosis of SMARCA4-deficient non-small cell carcinoma. The patient responded well to immune checkpoint inhibitors with nivolumab. However, new lesions with various pathological presentations and various responses to nivolumab appeared during the treatment course. The patient survived more than 3 years from the initial diagnosis. This case shows the efficacy of nivolumab to treat SMARCA4-deficient non-small cell lung carcinoma.

Usefulness of cell block examination for the cytological diagnosis of thoracic SMARCA4-deficient undifferentiated tumor: A case report

SMARCA4-deficient undifferentiated tumor (SMARCA4-UT) is a high-grade malignant neoplasm showing undifferentiated or rhabdoid morphology that significantly involves the thorax of adults. It has been reported as SMARCA4-deficient thoracic sarcoma or SMARCA4-deficient non-small cell lung carcinoma according to the findings of immunohistochemical and genetic studies. We report a case of thoracic SMARCA4-UT for which cell block analysis and immunohistochemical staining were useful for the final diagnosis. A 51-year-old man had a chief complaint of left back pain and visited our hospital for further examination. Cytological examination of a left pleural effusion was performed and we also made a cell block of the pleural effusion. Cytological examination revealed polyhedral to round tumor cells. The tumor cells appeared singly or formed loosely cohesive clusters. The nuclei were round to oval, enlarged, and sometimes eccentric with prominent nucleoli with irregular borders. The nuclear chromatin was unevenly distributed. The cytoplasm was vacuolar to eosinophilic. There were no characteristic structures of tumor cells. The cell block revealed many single or loosely cohesive round to epithelioid cells. Some tumor cells often exhibited eccentrically located nuclei and lightly eosinophilic cytoplasm, showing a rhabdoid morphology. On immunohistochemistry, the tumor cells were positive for SOX-2 and they demonstrated significantly reduced SMARCA4 (BRG1) expression; SMARCA2 (BRM) and SMARCB1 (INI1) expression were retained. Accordingly, we made a diagnosis of SMARCA4-UT. This case demonstrates the importance of performing histological and immunohistochemical analysis using cell blocks for immediate diagnosis.

SWI/SNF complex gene variations are associated with a higher tumor mutational burden and a better response to immune checkpoint inhibitor treatment: a pan-cancer analysis of next-generation sequencing data corresponding to 4591 cases

Background

Genes related to the SWItch/sucrose nonfermentable (SWI/SNF) chromatin remodeling complex are frequently mutated across cancers. SWI/SNF-mutant tumors are vulnerable to synthetic lethal inhibitors. However, the landscape of SWI/SNF mutations and their associations with tumor mutational burden (TMB), microsatellite instability (MSI) status, and response to immune checkpoint inhibitors (ICIs) have not been elucidated in large real-world Chinese patient cohorts.

Methods

The mutational rates and variation types of six SWI/SNF complex genes (ARID1A, ARID1B, ARID2, SMARCA4, SMARCB1, and PBRM1) were analyzed retrospectively by integrating next-generation sequencing data of 4591 cases covering 18 cancer types. Thereafter, characteristics of SWI/SNF mutations were depicted and the TMB and MSI status and therapeutic effects of ICIs in the SWI/SNF-mutant and SWI/SNF-non-mutant groups were compared.

Results

SWI/SNF mutations were observed in 21.8% of tumors. Endometrial (54.1%), gallbladder and biliary tract (43.4%), and gastric (33.9%) cancers exhibited remarkably higher SWI/SNF mutational rates than other malignancies. Further, ARID1A was the most frequently mutated SWI/SNF gene, and ARID1A D1850fs was identified as relatively crucial. The TMB value, TMB-high (TMB-H), and MSI-high (MSI-H) proportions corresponding to SWI/SNF-mutant cancers were significantly higher than those corresponding to SWI/SNF-non-mutant cancers (25.8 vs. 5.6 mutations/Mb, 44.3% vs. 10.3%, and 16.0% vs. 0.9%, respectively; all p  < 0.0001). Furthermore, these indices were even higher for tumors with co-mutations of SWI/SNF genes and MLL2/3. Regarding immunotherapeutic effects, patients with SWI/SNF variations showed significantly longer progression-free survival (PFS) rates than their SWI/SNF-non-mutant counterparts (hazard ratio [HR], 0.56 [95% confidence interval {CI} 0.44–0.72]; p < 0.0001), and PBRM1 mutations were associated with relatively better ICI treatment outcomes than the other SWI/SNF gene mutations (HR, 0.21 [95% CI 0.12–0.37]; p = 0.0007). Additionally, patients in the SWI/SNF-mutant + TMB-H (HR, 0.48 [95% CI 0.37–0.54]; p  < 0.0001) cohorts had longer PFS rates than those in the SWI/SNF-non-mutant + TMB-low cohort.

Conclusions

SWI/SNF complex genes are frequently mutated and are closely associated with TMB-H status, MSI-H status, and superior ICI treatment response in several cancers, such as colorectal cancer, gastric cancer, and non-small cell lung cancer. These findings emphasize the necessity and importance of molecular-level detection and interpretation of SWI/SNF complex mutations.

Case report: A rapid response to immunotherapy in a thoracic SMARCA4-deficient undifferentiated tumor with respiratory failure

Thoracic SMARCA4-deficient undifferentiated tumor (SMARCA4-UT) is an extremely rare and poor-prognosis malignancy, which has recently been noted as a subtype of lung tumors. We presented a case of SMARCA4-UT in a 50-year-old man with progressively worsening respiratory failure. The tumor was the first reported to involve pulmonary artery, and 90% of tumor cells expressed programmed cell death ligand 1 (PD-L1). High tumor mutational burden (TMB, 23.93/Mb) and mutations in SMARCA4 were detected. It is the first reported case to receive Tislelizumab monotherapy with considerable improvement in clinical condition and no adverse events. As a result of our case, we highlight the importance of recognizing SMARCA4-UT as an individual entity, as well as the efficacy of immune checkpoint inhibitor therapy, particularly in patients with high levels of TMB and PD-L1 expression.

Delineation of a SMARCA4-specific competing endogenous RNA network and its function in hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is a common malignancy worldwide, and the mortality rate continues to rise each year. SMARCA4 expression has been associated with poor prognosis in various types of cancer; however, the specific mechanism of action of SMARCA4 in HCC needs to be fully elucidated.

AIM

To explore the specific mechanism of action of SMARCA4 in HCC.

METHODS

Herein, the expression level of SMARCA4 as well as its association with HCC prognosis were evaluated using transcriptome profiling and clinical data of 18 different types of cancer collected from The Cancer Genome Atlas database. Furthermore, SMARCA4-high and -low groups were identified. Thereafter, gene ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses were performed to identify the function of SMARCA4, followed by construction of a SMARCA4-specific competing endogenous RNA (ceRNA) network using starBase database. The role of SMARCA4 in immunotherapy and its association with immune cells were assessed using correlation analysis.

RESULTS

It was observed that SMARCA4 was overexpressed and negatively correlated with prognosis in HCC. Further, SMARCA4 expression was positively associated with tumor mutational burden, microsatellite stability, and immunotherapy efficacy. The SNHG3/THUMP3-AS1-miR-139-5p-SMARCA4 ceRNA network was established and could be assumed to serve as a stimulatory mechanism in HCC.

CONCLUSION

The findings of this study demonstrated that SMARCA4 plays a significant role in progression and immune infiltration in HCC. Moreover, a ceRNA network was detected, which was found to be correlated with poor prognosis in HCC. The findings of this study could contribute towards the identification of predictive markers for immunotherapy and a novel mechanism of action for HCC treatment.

Nervous system (NS) Tumors in Cancer Predisposition Syndromes

Genetic syndromes which develop one or more nervous system (NS) tumors as one of the manifestations can be grouped under the umbrella term of NS tumor predisposition syndromes. Understanding the underlying pathological pathways at the molecular level has led us to many radical discoveries, in understanding the mechanisms of tumorigenesis, tumor progression, interactions with the tumor microenvironment, and development of targeted therapies. Currently, at least 7-10% of all pediatric cancers are now recognized to occur in the setting of genetic predisposition to cancer or cancer predisposition syndromes. Specifically, the cancer predisposition rate in pediatric patients with NS tumors has been reported to be as high as 15%, though it can approach 50% in certain tumor types (i.e., choroid plexus carcinoma associated with Li Fraumeni Syndrome). Cancer predisposition syndromes are caused by pathogenic variation in genes that primarily function as tumor suppressors and proto-oncogenes. These variants are found in the germline or constitutional DNA. Mosaicism, however, can affect only certain tissues, resulting in varied manifestations. Increased understanding of the genetic underpinnings of cancer predisposition syndromes and the ability of clinical laboratories to offer molecular genetic testing allows for improvement in the identification of these patients. The identification of a cancer predisposition syndrome in a CNS tumor patient allows for changes to medical management to be made, including the initiation of cancer surveillance protocols. Finally, the identification of at-risk biologic relatives becomes feasible through cascade (genetic) testing. These fundamental discoveries have also broadened the horizon of novel therapeutic possibilities and have helped to be better predictors of prognosis and survival. The treatment paradigm of specific NS tumors may also vary based on the patient's cancer predisposition syndrome and may be used to guide therapy (i.e., immune checkpoint inhibitors in constitutional mismatch repair deficiency [CMMRD] predisposition syndrome) [8]. Early diagnosis of these cancer predisposition syndromes is therefore critical, in both unaffected and affected patients. Genetic counselors are uniquely trained master's level healthcare providers with a focus on the identification of hereditary disorders, including hereditary cancer, or cancer predisposition syndromes. Genetic counseling, defined as "the process of helping people understand and adapt to the medical, psychological and familial implications of genetic contributions to disease" plays a vital role in the adaptation to a genetic diagnosis and the overall management of these diseases. Cancer predisposition syndromes that increase risks for NS tumor development in childhood include classic neurocutaneous disorders like neurofibromatosis type 1 and type 2 (NF1, NF2) and tuberous sclerosis complex (TSC) type 1 and 2 (TSC1, TSC2). Li Fraumeni Syndrome, Constitutional Mismatch Repair Deficiency, Gorlin syndrome (Nevoid Basal Cell Carcinoma), Rhabdoid Tumor Predisposition syndrome, and Von Hippel-Lindau disease. Ataxia Telangiectasia will also be discussed given the profound neurological manifestations of this syndrome. In addition, there are other cancer predisposition syndromes like Cowden/PTEN Hamartoma Tumor Syndrome, DICER1 syndrome, among many others which also increase the risk of NS neoplasia and are briefly described. Herein, we discuss the NS tumor spectrum seen in the abovementioned cancer predisposition syndromes as with their respective germline genetic abnormalities and recommended surveillance guidelines when applicable. We conclude with a discussion of the importance and rationale for genetic counseling in these patients and their families.

Comprehensive genomic profiling of Finnish lung adenocarcinoma cohort reveals high clinical actionability and SMARCA4 altered tumors with variable histology and poor prognosis

INTRODUCTION

Lung adenocarcinoma is the most common type of lung cancer and typically carries a high number of mutations. However, the genetic background of the tumors varies according to patients' ethnic background and smoking status. Little data is available on the mutational landscape and the frequency of actionable genomic alterations in lung adenocarcinoma in the Finnish population.

MATERIALS AND METHODS

We evaluated the gene alteration frequencies of 135 stage I-IV lung adenocarcinomas operated at Turku University Hospital between 2004 and 2017 with a large commercial comprehensive genomic profiling panel. Additionally, we correlated the alterations in selected genes with disease outcomes in 115 stage I-III patients with comprehensive follow-up data. The genomic alterations in a sub-cohort of 30 never-smokers were assessed separately.

RESULTS

Seventy percent of patients in the overall cohort and 77% in the never-smoker sub-cohort harbored an alteration or a genomic signature targetable by FDA and/or EMA approved drug for non-small cell carcinoma, respectively. In multivariable analysis for disease-specific survival, any alteration in SMARCA4 (DSS; HR 3.911, 95%CI 1.561-9.795, P=0.004) exhibited independent prognostic significance along with stage, tumor mutation burden, and predominant histological subtypes.

CONCLUSIONS

Over two thirds of our overall cohort, and especially never-smokers had an actionable genomic alteration or signature. SMARCA4 alterations, detected in 7.4% of the tumors, independently predicted a shortened overall and disease-specific survival regardless of the alteration type. Most SMARCA4 alterations in our cohort were missense mutations associated with differentiated predominant histological subtypes and immunohistochemical SMARCA4/BRG1 and TTF-1 positive status.

[Analysis of Clinicopathologic Features of 9 Cases of SMARCA4-deficient Non-small Cell Lung Cancer]

BACKGROUND

SMARCA4-deficient non-small cell lung cancer (SMARCA4-dNSCLC) is a rare primary lung malignancy. These diseases are not listed separately in the 2021 World Health Organization (WHO) classification of lung neoplasms, but they have special morphological, immunophenotypic and molecular genetic characteristics. This study aims to improve understanding of SMARCA4-dNSCLC by discussing the clinicopathological features, diagonosis and differential diagnosis of the disease.

METHODS

The clinical and imaging data of 9 cases of SMARCA4-dNSCLC diagnosed in Shanghai Changhai Hospital from January 2020 to March 2022 were collected. The clinicopathological features were analyzed by histological and immunohistochemical staining, and the literature was reviewed.

RESULTS

The median age of 9 patients was 65 years old. Six men were smokers. The average maximum diameter of tumor was 3.3 cm. Six cases had been metastasized. The imaging showed that it was an infiltrating mass with unclear boundary and 3 cases invaded the pleura. Nine cases were diagnosed as SMARCA4-dNSCLC, which mainly showed three pathological forms including classic lung adenocarcinoma, mucinous adenocarcinoma and poorly differentiated carcinoma. Poorly differentiated tumor cells are epithelioid, syncytial or rhabdomyoid, the cytoplasm was rich, the cytoplasm could be completely transparent to eosinophilic, eosinophilic globules or small abscesses could be seen, showing solid flakes, with more inflammatory cells and flake necrosis in the stroma. Immunohistochemistry showed that SMARCA4 was negative in all cases and eight cases demonstrated cytokeratin 5.2 (CAM5.2) and cytokeratin 7 (CK7) was diffusely strongly positive, p40 was negative, thyroid transcription factor-1 (TTF-1) was negative in 6 cases, partially positive in 2 cases and diffusely positive in 1 case.

CONCLUSIONS

SMARCA4-dNSCLC is a rare subtype of lung cancer with complex and diverse pathological morphology. The characteristic of immunohistochemical phenotype can assist in the diagnosis.

Correlation between the Treg/Thl7 Index and the Efficacy of PD-1 Monoclonal Antibody in Patients with Advanced Non-Small-Cell Lung Cancer Complicated with Chronic Obstructive Pulmonary Disease

Objective

It was to explore the correlation between regulatory T cells (Treg)/T helper cell 17 (Thl7) and the efficacy of receiving a programmed death protein-1 (PD-1) monoclonal antibody (mAb) in patients with advanced non-small-cell lung cancer (NSCLC) complicated with chronic obstructive pulmonary disease (COPD).

Methods

The research subjects were 82 patients who were clinically evaluated and treated in the Respiratory Department of Suqian Hospital connected with Xuzhou Medical University from January to December 2021. All of the patients were given PD-1 immunotherapy, and 50 healthy people were chosen as the control group. Classification was carried out according to tumor type and tumor stage. The levels of Th17 and Treg/Th17 in the peripheral blood of patients with different tumor-node-metastasis (TNM) stages and different types were compared, and the immune function, lung function (forced expiratory volume in one second/forced vital capacity (FEV1%/FVC), FEV1%, and FVC), and changes in inflammatory factors were compared before and after treatment. The levels of interleukin (IL)-17, IL-6, tumor necrosis factor (TNF)-α, and transforming growth factor (TGF)-β were compared between the two groups. The correlation between Th17 cells and Treg cells in the peripheral blood of patients with NSCLC complicated with COPD was analyzed.

Results

After treatment, the levels of IL-17, IL-6, TNF-α, and TGF-β in patients with NSCLC combined with COPD were notably superior to those in the control group (P < 0.05). The immune function and lung function of the patients were improved after treatment. There were 43 cases of squamous cell carcinoma, 30 cases of adenocarcinoma, and 9 cases of large cell carcinoma. The proportion of Th17 cells to CD4+ T cells in the blood of the three types of patients and the proportion of CD4⁺CD25^HiCD127^Lo regulatory T cells to CD4+ lymphocyte cells in Treg cells showed no considerable difference among the different case types (P > 0.05). No considerable difference was indicated in Treg/Th17 in peripheral blood between stage IIIB and stage IV lung cancer patients (P > 0.05). A positive linear correlation was revealed between Th17 cells and Treg cells in the peripheral blood of patients with NSCLC combined with COPD, R = 0.26, P = 0.039.

Conclusion

Treg and Th17 cells were shown to be much higher in lung cancer patients with COPD, which could lead to immunosuppression and tumor growth. PD-1 therapy for NSCLC has demonstrated efficacy and can improve patients' immunological state while being extremely safe.

Cytomorphologic and immunophenotypical analysis of SMARCA4 (BRG1)-deficient non-small cell lung carcinoma

INTRODUCTION

Inactivation of SMARCA4/BRG1 (Brahma-related gene 1), a member of the switch/sucrose nonfermentable subfamily of adenosine triphosphate-dependent chromatin remodeling complexes, has been demonstrated in a subset of non-small cell lung carcinomas (NSCLCs). However, the cytomorphologic features of SMARCA4-deficient NSCLCs (SMARCA4-dNSCLC) have only rarely been reported.

MATERIALS AND METHODS

Eight cytology cases of SMARCA4-dNSCLC and eight SMARCA4-retained NSCLC (SMARCA4-rNSCLC) cases were retrieved from our institution's database. These were compared cytologically and immunophenotypically.

RESULTS

All 8 patients with SMARCA4-dNSCLC had a smoking history, and 4 of 8 cases had a prior cancer history. Cytologically, the tumors demonstrated predominantly loosely cohesive and high-grade epithelioid cells with markedly pleomorphic nuclei and prominent nucleoli. Binucleated/multinucleated cells were seen in 5 cases. Six cases showed focal plasmacytoid morphology, and 2 cases showed necrosis. In contrast, in all 8 cases of SMARCA4-rNSCLC, the aspirates were predominantly cohesive with focal, loosely cohesive epithelioid cells showing mild to moderate pleomorphism and lacked necrosis. Only 1 case showed multinucleated cells. All 8 cases of SMARCA4-dNSCLC showed an immunoprofile similar to that of the SMARCA4-rNSCLC cases, including immunoreactivity for AE1/AE3, a lack of immunoreactivity for thyroid transcription factor-1/Napsin A, and p40/p63 but with a loss of BRG1 expression.

CONCLUSIONS

SMARCA4-dNSCLCs exhibited high-grade cytologic features with marked pleomorphism and might show multinucleation and plasmacytoid morphology. In contrast, SMARCA4-rNSCLCs often show mild to moderate pleomorphism with round to polygonal shapes. Both characteristically lack expression of lung adenocarcinoma/squamous markers. Increased awareness of their cytomorphologic features on fine needle aspiration can ensure consideration of the diagnosis.

Cytomorphologic features of SMARCA4-deficient non-small cell lung carcinoma and correlation with immunohistochemical and molecular features

BACKGROUND

SMARCA4/BRG1-deficient tumors and those that have loss of SMARCA/BRG1 have been described as various aggressive carcinomas and sarcomas, including a subset of non-small cell lung carcinoma (NSCLC). Cytomorphologic features of NSCLCs are yet to be described. The objective of this study was to evaluate the cytomorphologic features, immunohistochemical profile, and molecular profile of SMARCA4/BRG1-deficient NSCLC (SMARCA4-dNSCLC).

METHODS

The authors retrospectively searched for cases with SMARCA4/BRG1 functional loss alterations, which were identified in molecular studies and further confirmed by immunocytochemistry, and they reviewed the cytomorphologic features. Tumors with BRG1 loss were also stained with an extensive antibody panel. Molecular profiling and clinical information of the identified cases were scrutinized.

RESULTS

In total, 12 cytopathology cases from different anatomic sites were included. All cases showed variable expression of cytokeratin irrespective of type. One-half of cases had glandular features, followed by squamoid features, and poorly differentiated features. The most common cytologic features included sheets or papillary architecture, round or oval cell shapes, nuclear enlargement, moderate-to-marked pleomorphism, and coarse chromatin. Two cases with poorly differentiated cytomorphology had a predominance of single cells, scant cytoplasm, and macronucleoli. Variable expression of epithelial markers was noted in all cases. TP53 was the most frequently co-mutated gene in SMARCA4-dNSLCs.

CONCLUSIONS

This study demonstrates that SMARCA4-dNSCLCs can have a wide spectrum of cytomorphologic features, ranging from a relatively well differentiated adenocarcinoma to a poorly differentiated/undifferentiated carcinoma, with the majority of cases exhibiting some high-grade features, such as mitosis, apoptosis, necrosis, and marked pleomorphism.

Thorahcic SMARCA4-deficient undifferentiated tumors with ganglioneuroma and enchondroma: implications for SLC7A11 and ARID1A expression: a case report

Background

SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin, subfamily A, member 4-deficient thoracic sarcoma (SMARCA4-DTS) is a rare disease that has recently been described as an entity. It is characterized by an aggressive clinical course and specific genetic alterations. As an immunohistological feature, the tumors are deficient in SMARCA4 and SMARCA2 and express sex-determining region Y (SRY)-box 2 (SOX2). Occasionally, there are cases that are less frequent and difficult to distinguish from SMARCA4-deficient non-small cell lung carcinoma (SMARCA4-dNSCLC). Therefore, the 5th edition of the World Health Organization (WHO) classification describes thoracic SMARCA 4-deficient undifferentiated tumors (SMARCA4-UT). In contrast, Carney’s triad is a syndrome that combines three rare soft tissue tumors: gastric leiomyosarcoma, pulmonary chondroma, and extra-adrenal paraganglioma. Protein kinase cAMP-dependent type I regulatory subunit alpha (PRKAR1A) has been proposed as the causative gene. Both diseases are valuable cases; moreover, there have been no previous reports of their coexistence.

Case presentation

A 43-year-old man visited our hospital because of respiratory distress. Computed tomography revealed a large mass measuring 55 mm in the upper lobe of the right lung and front mediastinum, with metastases in the surrounding lymph nodes. Needle biopsy was performed for diagnosis, and histological examination of the samples revealed monotonous epithelioid-like cells with loose binding and sheet-form proliferation. The tumor cells had distinct nuclei with some rhabdoid-like cells. Immunohistochemical analysis revealed that the tumor cells were positive for AE1AE3, SOX2, CD34, and p53 and negative for SMARCA4 and SMARCA2. The patient died 6 months after admission, without any treatment. Autopsy revealed ganglioneuroma and enchondroma suggestive of an incomplete Carney complex.

Conclusion

SMARCA4-UT is a rare and recently established disease. While it is difficult to diagnose, it is necessary to distinguish undifferentiated carcinoma, large cell carcinoma, Ewing sarcoma, and epithelioid sarcoma when diagnosing tumors involving the mediastinum. Moreover, cases of SMARCA4-UT with ganglioneuroma and enchondroma are very rare. We discuss and report a case of SMARCA4-UT in which we also examined ARID1A and SLC7A11expression.

Thoracic SMARCA4-deficient undifferentiated tumor-a case of an aggressive neoplasm-case report

Thoracic SMARCA4-deficient undifferentiated tumors (SMARCA4-UT) are aggressive neoplasms that most commonly occur in the mediastinum of male smokers. These tumors are characterized by an inactivating mutation of SMARCA4 resulting in loss of expression of brahma-related gene 1 (BRG1). These tumors can have a variable immunophenotype but in general have no or only focal keratin expression and characteristically lack expression of BRG1. Most patients have metastatic disease at time of presentation. Usually SMARCA4-UT progress or recur and the median survival of these patients is only approximately half a year. Preclinical and clinical trials using enhancer of zeste homolog (EZH2) inhibitors are underway to potentially treat this neoplasm. In addition, rare cases of successful treatment with anti-PD-1 inhibitors are described. Here, the case of a 66-year-old male smoker who presents with mediastinal and left suprahilar masses and widespread metastatic disease is reported. A biopsy reveals extensive necrosis and clusters and small sheets of neoplastic epithelioid cells with some exhibiting rhabdoid cytology. The tumor cells lack staining with various keratins and markers of lymphoid, melanocytic, myogenic, or vascular differentiation. Focal expression of CD30 is noted. BRG1 expression is lost in the tumor cells while INI-1 expression is preserved. This tumor is diagnosed as SMARCA4-UT.

Molecular and immunophenotypic characterization of SMARCB1 (INI1) - deficient intrathoracic Neoplasms

The switch/sucrose-non-fermenting (SWI/SNF) complex is an ATP-dependent chromatin remodeling complex that plays important roles in DNA repair, transcription and cell differentiation. This complex consists of multiple subunits and is of particular interest in thoracic malignancies due to frequent subunit alteration of SMARCA4 (BRG1). Much less is known about SMARCB1 (INI1) deficient intrathoracic neoplasms, which are rare, often misclassified and understudied. In a retrospective analysis of 1479 intrathoracic malignant neoplasms using immunohistochemistry for INI1 (SMARCB1) on tissue micro arrays (TMA) and a search through our hospital sarcoma database, we identified in total nine intrathoracic, INI1 deficient cases (n = 9). We characterized these cases further by additional immunohistochemistry, broad targeted genomic analysis, methylation profiling and correlated them with clinical and radiological data. This showed that genomic SMARCB1 together with tumor suppressor alterations drive tumorigenesis in some of these cases, rather than epigenetic changes such as DNA methylation. A proper diagnostic classification, however, remains challenging. Intrathoracic tumors with loss or alteration of SMARCB1 (INI1) are highly aggressive and remain often underdiagnosed due to their rarity, which leads to false diagnostic interpretations. A better understanding of these tumors and proper diagnosis is important for better patient care as clinical trials and more targeted therapeutic options are emerging.

SMARCA4/BRG1-Deficient Sinonasal Carcinoma: Morphologic Spectrum of an Evolving Entity

CONTEXT.—

Molecular analysis of poorly differentiated/undifferentiated sinonasal neoplasms has resulted in identification of a growing number of genetically defined tumors. SMARCA4-deficient sinonasal carcinoma is one such recently described entity that emerged from within sinonasal undifferentiated carcinoma (SNUC), neuroendocrine carcinoma (NEC), and teratocarcinosarcoma (TCS).

OBJECTIVE.—

To identify SMARCA4-deficient sinonasal carcinomas from a large institutional cohort of poorly differentiated/undifferentiated carcinomas and evaluate their clinicopathologic features.

DESIGN.—

SMARCA4/BRG1 immunohistochemistry was performed on all tumors diagnosed as SNUC, poorly differentiated carcinoma, NEC, and TCS during a 12-year period. SMARCA2/BRM and INSM1 immunostaining was performed in SMARCA4-deficient cases.

RESULTS.—

Twelve SMARCA4-deficient sinonasal carcinomas were identified among 299 cases. Morphologically, 5 cases were large cell NEC, 2 cases were small cell NEC, and 5 were TCS. SMARCA4 loss was diffuse and complete in 10 cases, while 2 cases showed focal retention. Most cases showed diffuse cytokeratin staining accompanied by weak, usually focal staining for chromogranin and synaptophysin. INSM-1 showed negativity in most cases. All cases showed retained SMARCA2 expression. IDH1/2 mutation was absent in all cases analyzed. Four of 7 patients died of disease, and aggressive multimodality treatment had better outcome.

CONCLUSIONS.—

SMARCA4-deficient sinonasal carcinomas are morphologically akin to sinonasal poorly differentiated NECs and TCS, display cytokeratin positivity and only focal staining for neuroendocrine markers, and have aggressive biological behavior. Inclusion of SMARCA4 in the immunohistochemical panel for diagnostic workup of all sinonasal NEC and TCS phenotypes will facilitate their early recognition. Comprehensive germline and somatic mutational analyses of these tumors are necessary for further insights into their molecular pathogenesis.

TTF1-positive SMARCA4/BRG1 deficient lung adenocarcinoma

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.

Expanding the Immunophenotype Spectrum of SMARCA4-Deficient Non-Small Cell Lung Carcinomas: A Case Series with Neuroendocrine Markers Expression

Aims. In recent years, SMARCA4-deficient nonsmall cell lung cancer (NSCLC) has been recognized as a distinct new subtype of lung cancer, which is characterized by loss of SMARCA4 (Brahma-related gene-1 [BRG1]) protein expression. Only a limited number of SMARCA4-deficient NSCLC case series have been reported, and their clinicopathological features have not yet been fully elucidated. Our main aim was to analyze the clinical history, histology, immunohistochemistry, and molecular pathology of 5 SMARCA4-deficient NSCLC patients with poorly differentiated or undifferentiated histology and neuroendocrine markers expression. Methods and results. Five patients with complete loss of nuclear BRG1 immunostaining were identified among 53 patients of poorly differentiated/undifferentiated NSCLC. We then performed immunohistochemical staining and gene mutation analysis using a real-time polymerase chain reaction. All patients were male aged between 58 and 82 years (average 67.6 years), with smoking exposure. Histologically, the tumors had a relatively monotonous morphology and showed solid nest-like, sheet-like growth, and geographic necrosis. Thyroid transcription factor 1, cytokeratin 7, and Napsin A were all negative (5 of 5). Moreover, all tumors showed a variable expression of neuroendocrine markers, including synaptophysin, chromogranin A and CD56. Hot spot epidermal growth factor receptor/anaplastic large-cell lymphoma kinase/c-ros oncogene 1 mutations were not detected in any of the 5 tumors. Conclusions. To the best of our knowledge, this is the first study that has reported the poorly differentiated morphology with a frequent expression of neuroendocrine markers. Our results have expanded the immunophenotype spectrum of SMARCA4-deficient NSCLC. However, the clinicopathological significance of this subset of SMARCA4-deficient NSCLC should be further clarified in larger series studies.

SMARCA4/BRG1 protein-deficient thoracic tumors dictate re-examination of small biopsy reporting in non-small cell lung cancer

Background

SMARCA4/BRG1 protein–deficient lung adenocarcinomas and thoracic sarcoma are recently described entities that lack distinctive histological features, transcription termination factor 1 (TTF1) reactivity, and actionable driver mutations. The current diagnostic path for small lung biopsies as recommended by the World Health Organization (WHO, 2015) is likely to categorize these as non–small cell carcinoma–not otherwise specified (NSCC-NOS). The present study attempts to define the subtle but distinctive clinicopathologic features of SMARCA4/BRG1 protein-deficient thoracic tumors; highlight their unique biology; and addresses the unmet need to segregate these using a new, tissue-proficient diagnostic pathway.

Methods

All lung biopsies and those from metastatic sites in patients with suspected advanced lung cancer and classified as NSCC-NOS as per WHO (2015) guidelines were subjected to BRG1 testing by immunohistochemistry. SMARCA4/BRG1 protein–deficient thoracic tumors were evaluated by an extended immunohistochemistry panel. Predictive biomarker and programmed death–ligand 1 testing was conducted in all cases.

Results

Of 110 cases, nine were found to be SMARCA4/BRG1 protein-deficient; six were identified as SMARCA4/BRG1 protein–deficient lung adenocarcinomas, and three were SMARCA4/BRG1 protein-deficient thoracic sarcomas. The histology ranged from poorly differentiated to undifferentiated to rhabdoid. None of the cases showed significant expression of TTF1 or p40, and no actionable mutation was identified.

Conclusions

It is difficult to separate BRG1-deficient lung adenocarcinomas and thoracic sarcomas based on morphology alone. We propose a diagnostic pathway for small biopsies of thoracic tumors to segregate these distinct entities so that they can be studied more efficaciously for new biomarkers and therapeutic options.

What Is New in Biomarker Testing at Diagnosis of Advanced Non-Squamous Non-Small Cell Lung Carcinoma? Implications for Cytology and Liquid Biopsy

The discovery and clinical validation of biomarkers predictive of the response of non-squamous non-small-cell lung carcinomas (NS-NSCLC) to therapeutic strategies continue to provide new data. The evaluation of novel treatments is based on molecular analyses aimed at determining their efficacy. These tests are increasing in number, but the tissue specimens are smaller and smaller and/or can have few tumor cells. Indeed, in addition to tissue samples, complementary cytological and/or blood samples can also give access to these biomarkers. To date, it is recommended and necessary to look for the status of five genomic molecular biomarkers (EGFR, ALK, ROS1, BRAFV600, NTRK) and of a protein biomarker (PD-L1). However, the short- and more or less long-term emergence of new targeted treatments of genomic alterations on RET and MET, but also on others’ genomic alteration, notably on KRAS, HER2, NRG1, SMARCA4, and NUT, have made cellular and blood samples essential for molecular testing. The aim of this review is to present the interest in using cytological and/or liquid biopsies as complementary biological material, or as an alternative to tissue specimens, for detection at diagnosis of new predictive biomarkers of NS-NSCLC.

Recent updates in thoracic SMARCA4-deficient undifferentiated tumor

Germline inactivating mutations in SMARCA4 (SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin, subfamily A, member 4) gene encoding for BRG1 (Brahma related gene-1) are the molecular drivers in small cell carcinoma of ovary, hypercalcemic type (SCCOHT) and in malignant rhabdoid tumors (MRT) that occur in the context of rhabdoid tumor predisposition syndrome-type 2. Somatic SMARCA4 mutations and/or loss of BRG1 have been identified in a variety of adult-onset epithelial and mesenchymal neoplasms. Among thoracic tumors, these include subsets of smoking-related non-small cell lung carcinoma (NSCLC) and a relatively rare, newly recognised tumor entity: thoracic SMARCA4-deficient undifferentiated tumor (SMARCA4-UT). Less than 100 cases of SMARCA4-UT have been reported to date. They present as large compressive and infiltrative mediastinal, lung and/or pleural masses in middle-aged male smokers. They are undifferentiated tumors composed of sheets of small/epithelioid and/or rhabdoid tumor cells variably expressing epithelial markers and consistently showing loss of BRG1 and the closely related protein, Brahma (BRM). Frequent expression of stem cell markers (SOX2, CD34, SALL4) is noted. Despite gene expression profiles similar to MRTs and SCCOHT, they show striking genomic overlap with SMARCA4-mutant NSCLC with frequent TP53, STK11, KEAP1, and KRAS mutations, high tumor mutation burden (TMB), and presence of smoking related molecular signatures in tumor cells. SMARCA4-UT show uniformly poor survival and are irresponsive to conventional therapies. Immunotherapy responses are variable but promising, although PDL1 expression appears to be of poor predictive value. Drugs exploiting genetic and epigenetic mechanisms of SMARCA4 antagonism hold promise for future targeted therapies.

Advances in cytology of lung cancer

Cytopathology has emerged as a promising platform in precision oncology especially after the revolutionary change in our understanding of the concept of lung cancer etiopathogenesis. With increasing use of minimally invasive techniques for sample acquisition, it becomes almost mandatory to utilize precious cytology samples maximally and judiciously by appropriate triaging of the specimen and timely action of the cytopathology team. Existing patient management protocols require accurate morphologic and molecular diagnosis of the lung cancer specimens which needs knowledge about evolving techniques related to specimen procurement, updates of genomic variants of lung cancer and recently developed molecular testing platforms and algorithms which are capable enough to use even miniscule amount of diagnostic material. This review provides a brief knowledge about advances in cytology of lung cancer which are helpful for developing correct clinical management strategies.

A Challenging Task: Identifying Patients with Cancer of Unknown Primary (CUP) According to ESMO Guidelines: The CUPISCO Trial Experience

BACKGROUND

CUPISCO is an ongoing randomized phase II trial (NCT03498521) comparing molecularly guided therapy versus platinum-based chemotherapy in patients newly diagnosed with "unfavorable" cancer of unknown primary (CUP).

MATERIALS AND METHODS

Patients with an unfavorable CUP diagnosis, as defined by the European Society of Medical Oncology (ESMO), and available cancer tissue for molecular sequencing are generally eligible. Potential patients with CUP entering screening undergo a review involving reference histopathology and clinical work-up by a central eligibility review team (ERT). Patients with "favorable" CUP, a strongly suspected primary site of origin, lack of tissue, or unmet inclusion criteria are excluded.

RESULTS

As of April 30, 2020, 628 patients had entered screening and 346 (55.1%) were screen failed. Screen fails were due to technical reasons (n = 89), failure to meet inclusion and exclusion criteria not directly related to CUP diagnosis (n = 89), and other reasons (n = 33). A total of 124 (35.8%) patients were excluded because unfavorable adeno- or poorly differentiated CUP could not be confirmed by the ERT. These cases were classified into three groups ineligible because of (a) histologic subtype, such as squamous and neuroendocrine, or favorable CUP; (b) evidence of a possible primary tumor; or (c) noncarcinoma histology.

CONCLUSION

Experience with CUPISCO has highlighted challenges with standardized screening in an international clinical trial and the difficulties in diagnosing unfavorable CUP. Reconfirmation of unfavorable CUP by an ERT in a clinical trial can result in many reasons for screen failures. By sharing this experience, we aim to foster understanding of diagnostic challenges and improve diagnostic pathology and clinical CUP algorithms.

IMPLICATIONS FOR PRACTICE

A high unmet need exists for improved treatment of cancer of unknown primary (CUP); however, study in a trial setting is faced with the significant challenge of definitively distinguishing CUP from other cancer types. This article reports the authors' experience of this challenge so far in the ongoing CUPISCO trial, which compares treatments guided by patients' unique genetic signatures versus standard chemotherapy. The data presented will aid future decision-making regarding diagnosing true CUP cases; this will have far-reaching implications in the design, execution, and interpretation of not only CUPISCO but also future clinical studies aiming to find much-needed treatment strategies.

Cytology of SMARCA4-Deficient Thoracic Neoplasms: Comparative Analysis of SMARCA4-Deficient Non-Small Cell Lung Carcinomas and SMARCA4-Deficient Thoracic Sarcomas

INTRODUCTION

Inactivating mutations of the SMARCA4 (SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin, subfamily A, member 4) gene and/or loss of the BRG1 (brahma-related gene 1) protein defines SMARCA4-deficient thoracic sarcoma (SMARCA4-dTS), an aggressive neoplasm with a usually fatal outcome. Similar SMARCA4 mutations/BRG1 loss is also seen in a subset of non-small cell lung carcinomas (NSCLCs; SMARCA4-dNSCLCs) that lack alterations in currently targetable oncogenic drivers, that is, EGFR, ALK, and ROS1. There is limited knowledge on the cytomorphological features of these SMARCA4-deficient thoracic neoplasms.

METHODS

We retrospectively analysed the cytology of 2 cases each of SMARCA4-dNSCLC and SMARCA4-dTS to understand their cytomorphological overlap, if any, and identify features that would prompt testing for BRG1 loss.

RESULTS

All 4 patients were males presenting with advanced disease, with a mean age of 41.5 years (SMARCA4-dTS) and 58.5 years (SMARCA4-dNSCLC) at presentation. The cytology of the 2 SMARCA4-dTSs was strikingly similar, showing predominantly singly dispersed rhabdoid phenotype tumour cells with perinuclear cytoplasmic condensations in an inflammatory or necrotic background. The cytology raised suspicion for a wide range of differentials, including melanoma, high-grade lymphoma, germ cell tumour, undifferentiated carcinoma, and undifferentiated sarcoma. SMARCA4-dNSCLCs, on the other hand, were recognizable as poorly differentiated (adeno)carcinomas and were easily distinguished from SMARCA4-dTSs, with both cases showing cohesive clusters of frequently large tumour cells with abundant pale cytoplasm.

CONCLUSION

A diagnosis of SMARCA4-dTS is possible on cytology with appropriate ancillary testing and a high index of suspicion. The cytology of SMARCA4-dNSCLCs does not overlap with SMARCA4-dTS; rather, it resembles that of any poorly differentiated (adeno)carcinoma in the limited numbers analysed in this study.