"Sarcomatoid" carcinomas of the lung: a clinicopathological study of 86 cases with a new perspective on tumor classification

3D‑printed template‑guided iodine‑125 seed implantation to treat complete occlusion of the superior vena cava in pulmonary sarcomatoid carcinoma: A case report

Pulmonary sarcomatoid carcinoma (PSC), which is a type of non-small-cell lung carcinoma (NSCLC), is characterized by a high degree of malignancy, poor differentiation and a high incidence of pulmonary malignancy. In addition, PSC has a stronger invasive ability than other types of NSCLC and is not sensitive to radiation or chemotherapy. Furthermore, 90% of PSC cases exhibit vascular invasion; therefore, there is a risk of multiple metastases to the lung, bone, adrenal glands and brain, and consequently a poor prognosis, in the early stage. Targeted therapy and immunotherapy currently offer a new treatment direction; however, there have not been any significant advances in localized treatment in recent years. Thus, there is an urgent need for new localized treatment strategies. The present study describes the case of a 65-year-old man with recurrence of PSC after multi-line treatment with chemotherapy, radiotherapy, gamma knife and argon-helium knife treatment. In addition, the patient developed superior vena cava syndrome, and exhibited severe compression of the superior vena cava, chest discomfort, dyspnea and severe facial edema after chemotherapy, local gamma knife therapy (35 Gy, delivered through 14 2.5-Gy doses), argon-helium knife therapy and radiation therapy (28 Gy, delivered through seven 4-Gy doses). Partial remission was achieved after local implantation of iodine-125 (I125) seed under the guidance of a 3D-printed template, with progression-free survival observed up to 8 months afterwards. In conclusion, in patients with PSC who develop superior vena cava blockage after numerous treatment regimens, salvage I125 brachytherapy with a 3D-printed template may be suitable, and may improve local control and symptoms.

Tracing Tumor Heterogeneity of Pleomorphic Carcinoma of the Lung

INTRODUCTION

Pulmonary pleomorphic carcinoma (PPC) is an aggressive and highly heterogeneous NSCLC whose underlying biology is still poorly understood.

METHODS

A total of 42 tumor areas from 20 patients with PPC were microdissected, including 39 primary tumors and three metastases, and the histologically distinct components were subjected to whole exome sequencing separately. We further performed in silico analysis of microdissected bulk RNA sequencing and methylation data of 28 samples from 14 patients with PPC. We validated our findings using immunohistochemistry.

RESULTS

The epithelial and the sarcomatoid components of PPCs shared a large number of genomic alterations. Most mutations in cancer driver genes were clonal and truncal between the two components of PPCs suggesting a common ancestor. The high number of alterations in the RTK-RAS pathway suggests that it plays an important role in the evolution of PPC. The metastases morphologically and genetically resembled the epithelial or the sarcomatoid components of the tumor. The transcriptomic and epigenetic profiles of the sarcomatoid components of PPCs with matched squamous-like or adenocarcinoma-like components differed from each other, and they shared more similarities to their matched epithelial components. NCAM1/CD56 was preferentially expressed in the sarcomatoid component of squamous-like PPCs, whereas CDH1/E-Cadherin expression was down-regulated in the sarcomatoid component of most PPCs.

CONCLUSION

Lung adenocarcinoma-like PPCs are mainly driven by RTK-RAS signaling, whereas epithelial-mesenchymal transition programs as highlighted by increased NCAM1 and decreased CDH1 expression govern the epithelial-sarcomatoid transition between the clonally related tumor components. Several alterations in PPCs pinpoint therapeutic opportunities.

Novel model for cancer-specific survival of patients with pulmonary sarcomatoid carcinoma: A population-based analysis and external validation

BACKGROUND/OBJECTIVE

We aimed to develop a comprehensive and effective nomogram for predicting cancer-specific survival (CSS) in patients with pulmonary sarcomatoid carcinoma (PSC).

METHODS

Data for patients diagnosed with PSC between 2004 and 2018 from the Surveillance, Epidemiology, and End Results database were retrospectively collected and randomly divided into training and internal validation sets. We then retrospectively recruited patients diagnosed with PSC to construct an external validation cohort from the Southwest Hospital. A prognostic nomogram for CSS was established using independent prognostic factors that were screened from the multivariate Cox regression analysis. The performance of the nomogram was evaluated using area under the receiver operating characteristic (ROC) curves, Harrell's concordance index (C-index), calibration diagrams, and decision curve analysis (DCA). The clinical value of the nomogram and tumor, nodes, and metastases (TNM) staging system was compared using the C-index and net reclassification index (NRI).

RESULTS

Overall, 1356 patients with PSC were enrolled, including 876, 377, and 103 in the training, internal validation, and external validation sets, respectively. The C-index and ROC curves, calibration, and DCA demonstrated satisfactory nomogram performance for CSS in patients with PSC. In addition, the C-index and NRI of the nomogram suggested a significantly higher nomogram value than that of the TNM staging system. Subsequently, a web-based predictor was developed to help clinicians obtain this model easily.

CONCLUSIONS

The prognostic nomogram developed in this study can conveniently and precisely estimate the prognosis of patients with PSC and individualize treatment, thereby assisting clinicians in their shared decision-making with patients.

Primary Pulmonary Carcinomas with Spindle and/or Giant Cell Features: A Review with Emphasis in Classification and Pitfalls in Diagnosis

Primary carcinomas of the lung are vastly represented by the conventional types of adenocarcinomas or squamous cell carcinomas. However, there are other types of non-small cell carcinomas that although uncommon represent a meaningful group that often pose a problem not only in diagnosis but also in classification. Spindle cell and/or giant cell carcinomas, although uncommon represent an important group of primary lung carcinomas. Important to highlight is that current criteria are rather ambiguous and likely not up to date, which renders the classification of these tumors somewhat more obscure. In addition, with the daily use of immunohistochemical stains, the classification of these tumors may also pose a different problem in the proper allocation of these tumors. Proper classification is highly important in the selection process that takes place using such material for molecular analysis. The current molecular characteristics of these tumors are limited and lack more in-depth studies and analyses that can provide specific targets for the treatment of patients with these tumors. The current review attempts to highlight the shortcomings in the current classification and definitions of these neoplasms as well as the more current view regarding these tumors when the use of immunohistochemical stains is employed.

Chemotherapy for advanced pulmonary sarcomatoid carcinoma: a population-based propensity score matching study

OBJECTIVES

Pulmonary sarcomatoid carcinoma (PSC) is a rare histological type of non-small cell lung cancer (NSCLC). There are no specific treatment guidelines for PSC. For advanced PSC (stage II-IV), the role of chemotherapy is still controversial. The purpose of this study was to investigate the effect of chemotherapy on the prognosis of advanced PSC.

METHODS

A total of 960 patients with advanced PSC from the Surveillance, Epidemiology, and End Results (SEER) database between 2010 and 2019 were enrolled in this study. To investigate the prognostic factors, the Cox proportional hazard regression model was conducted. A total of 642 cases were obtained after propensity score matching (PSM). The Kaplan‒Meier method was applied to compare overall survival (OS) and cancer-specific survival (CSS).

RESULTS

For all 960 cases included in this study, the Cox proportional hazard model was applied for prognostic analysis. Univariate and multivariate analyses showed that stage, T stage, N stage, M stage, surgery, and chemotherapy were prognostic factors for OS and CSS (P < 0.05). A total of 642 cases were obtained after PSM, with no significant difference between the two groups for all variables. Kaplan‒Meier curves indicated that for OS and CSS, the prognosis was significantly better in the chemotherapy group than in the no-chemotherapy group.

CONCLUSIONS

For advanced PSC, chemotherapy can significantly improve the OS and CSS of patients. Chemotherapy should be an important part of PSC treatment.

The Correlation Between Histologic, Immunophenotypic, and Molecular Characteristics of Pulmonary Sarcomatoid Carcinoma Reveals That Sarcomatoid Change Is Potentially Derived From Epithelial Carcinoma Cells Undergoing Epithelial-Mesenchymal Transition

Pulmonary sarcomatoid carcinoma (PSC) is characterized by biphasic tumors with epithelial and mesenchymal phenotype. Little is known about the correlation between histologic, immunophenotypic features and the genetic profile of PSC. We analyzed the expression of epithelial-mesenchymal transition-related markers, adenocarcinoma (ADC) and squamous cell carcinoma lineage-specific markers of 205 PSC cases. The alteration of 5 targeted genes was detected by amplification-refractory mutation system-polymerase chain reaction. The intensity of cytokeratin staining was stronger in epithelial carcinoma (EC) than that of the sarcomatoid component (SC) of pleomorphic carcinoma, while vimentin was positive in only 16.3% (17/104) of EC of pleomorphic carcinoma. There is no significant difference between thyroid transcription factor 1 (TTF-1) expression in the SC (46.5%, 33/71) of pleomorphic carcinoma with ADC components and pure PSC (44.2%, 42/95) without p40 expression ( P =0.858). Four cases with ALK rearrangement were confirmed to co-express ALK fusion protein in both the SC and EC. The incidence of EGFR/ALK/KRAS mutation was similar between pleomorphic carcinoma with ADC components (40.6%, 26/64) and TTF-1 + pure PSC (38.2%, 13/34) ( P =0.583). However, higher proportions of TTF-1 + /p40 - PSC patients (44.8%, 39/87) had EGFR/ALK/KRAS mutation than those with TTF-1 - /p40 - PSC (16.7%, 4/24) ( P =0.031). The incidence of EGFR mutation was significantly higher in TTF-1-positive (18.4%, 16/87) than TTF-1-negative (2.7%, 2/74) PSC ( P =0.002). No EGFR and ALK abnormality were observed in 24 pleomorphic carcinoma cases with squamous cell carcinoma components or pure PSC with p40 expression. Our study reveals a close correlation between SC and EC components of pleomorphic carcinoma in terms of immunophenotypic and genetic features, which suggests that pleomorphic carcinoma is potentially derived from the sarcomatoid change of EC cells undergoing epithelial-mesenchymal transition.

Adjuvant chemotherapy is not a decisive factor in improving the overall survival of pulmonary sarcoma: A population-based study

Objective

This study aimed to investigate the impact of adjuvant chemotherapy on overall survival (OS) for pulmonary sarcomatoid carcinoma (PSC) and non-small-cell lung cancer (NSCLC) cohorts and to identify its potential risk factors.

Methods

A retrospective analysis was performed by querying the Surveillance, Epidemiology, and End Results (SEER) database for patients diagnosed as having PSC (n=460) and NSCLC (n=140,467) from 2004 to 2015. The demographics, tumor characteristics, treatment modes, and survival were included in the scope of statistical analysis. Confounding factors were controlled by propensity score matching (PSM) analysis. Kaplan–Meier survival curves were performed to compare the effects of adjuvant chemotherapy on OS of the patients in the two cohorts (PSC vs. NSCLC). A multivariable Cox regression model was constructed, and Kaplan–Meier analysis on each variate was applied to predict risk factors associated with OS.

Results

When adjuvant chemotherapy approach was applied in the treatment of patients with PSC or adjusted NSCLC, respectively, an improved OS could be observed in the NSCLC cohort (p=0.017). For the entire PSC cohort, 1-, 3-, and 5-year OS were 25.43%, 13.04%, and 6.96%, respectively, compared with 41.96%, 17.39%, and 10.00%, respectively, for the new adjusted NSCLC cohort after PSM, which were statistically significant difference (p<0.001). Multivariable Cox regression analysis was performed on OS covering prognostic factors such as primary site (p=0.036), first malignant indicator (p<0.001), age at diagnosis (p<0.001), marital status at diagnosis (p=0.039), and high school education (p=0.045). Additionally, patients with the following parameters had the worse impact on OS: a poorly differentiated pathology (Grade III/IV, p=0.023), older age (p<0.001), liver or lung metastasis (p=0.004, p=0.029), and the number of lymph nodes removed <4 (p<0.001).

Conclusions

Adjuvant chemotherapy did not play a decisive role in improving the OS of PSC, while it was associated with improved OS of NSCLC.

Characteristics and clinical outcomes of pulmonary sarcomatoid carcinoma: experience from Tata Memorial Centre

Background

Pulmonary sarcomatoid carcinoma (PSC) constitutes a heterogeneous group of poorly differentiated non-small cell lung cancers. Since these are rare tumours, we sought to determine the characteristics and clinical outcomes of these patients treated at our centre.

Methods

We did a retrospective evaluation of all patients diagnosed with PSC between January 2013 and September 2020 at the Tata Memorial Hospital, Mumbai, India. Baseline demographic and treatment data and outcomes were obtained retrospectively from electronic medical records and survival was calculated by using the Kaplan-Meier method.

Results

Out of 151 patients diagnosed with PSC during this period, 129 were included in the final analysis. The clinical stage was stage I in 3 (2.03%), stage II in 4 (3.1%), stage III in 35 (27.1%) and stage IV in 87 (67.4%). The median follow-up duration was 32 months (range, 15.0-48.9). The median overall survival (OS) of patients who received curative surgery was 18 months (95% confidence interval (95% CI), 2.59-33.4); concurrent chemoradiation was 11 months (95% CI, 2.99-19); palliative chemotherapy was 8 months (95% CI, 5.24-10.75) and best supportive care was 1 month (95% CI, 0.43-1.57, p = 0.001). On multivariate analysis, the presence of brain metastasis (p = 0.018; hazard ratio (HR), 2.47; 95% CI, 1.34-4.49) and the administration of chemotherapy (p = 0.037; HR, 2.2; 95% CI, 1.04-4.94) were the only factors impacting the OS.

Conclusion

PSC usually presents in advanced stages and is associated with a poor prognosis.

Pten and p53 Loss in the Mouse Lung Causes Adenocarcinoma and Sarcomatoid Carcinoma

Simple Summary

Lung cancer is the world leading cause of cancer death. Therefore, a better understanding of the disease is needed to improve patient survival. In this work, we have deleted the tumor suppressor genes Pten and Trp53 in adult mouse lungs to analyze its impact on tumor formation. Double mutant mice develop Adenocarcinoma and Pulmonary Sarcomatoid Carcinoma, two different types of Non-Small Cell Carcinoma whose biological relationships are a matter of debate. The former is very common, with various models described and some therapeutic options. The latter is very rare with very poor prognosis, no effective treatment and lack of models reported so far. Interestingly, this study reports the first mouse model of pulmonary sarcomatoid carcinoma available for preclinical research.

Abstract

Lung cancer remains the leading cause of cancer deaths worldwide. Among the Non-Small Cell Carcinoma (NSCLC) category, Adenocarcinoma (ADC) represents the most common type, with different reported driver mutations, a bunch of models described and therapeutic options. Meanwhile, Pulmonary Sarcomatoid Carcinoma (PSC) is one of the rarest, with very poor outcomes, scarce availability of patient material, no effective therapies and no models available for preclinical research. Here, we describe that the combined deletion of Pten and Trp53 in the lungs of adult conditional mice leads to the development of both ADC and PSC irrespective of the lung targeted cell type after naphthalene induced airway epithelial regeneration. Although this model shows long latency periods and incomplete penetrance for tumor development, it is the first PSC mouse model reported so far, and sheds light on the relationships between ADC and PSC and their cells of origin. Moreover, human ADC show strong transcriptomic similarities to the mouse PSC, providing a link between both tumor types and the human ADC.

Establishment of a Competing Risk Nomogram in Patients with Pulmonary Sarcomatoid Carcinoma

Background and aim: Pulmonary sarcomatoid carcinoma (PSC) is a rare subtype of nonsmall cell lung cancer with a poor prognosis. This study aimed to analyze the clinicopathological characteristics and survival outcomes among patients with PSC, lung squamous cell cancer (SCC), and lung adenocarcinoma (LAC), and to construct a competing risk nomogram for patients with PSC. Method: Data of 3 groups of patients diagnosed with PSC, SCC, or LAC from the surveillance, epidemiology, and end results (SEER) database between 1988 and 2015 were retrospectively reviewed. A 1:1 propensity score matching (PSM) analysis was used to balance the baseline data of patients. Independent risk factors associated with survival outcomes were screened by the least absolute shrinkage and selection operator and further determined by univariate and multivariate Cox proportional risk regression analyses. The overall survival (OS) of patients was evaluated by Kaplan–Meier analysis and compared with a log-rank test. The cumulative incidence function was used to estimate the 5-year probabilities of the cancer-specific mortality of PSC. A nomogram was constructed to illustrate the competing risk model to predict the 3- and 5-year OS, and corresponding concordance indexes (C-indexes) and calibration curves were used to assess and validate the competing risk nomogram. Results: A total of 2285 patients with PSC were included in this study. Compared with SCC and LAC patients, the Kaplan–Meier analysis showed that patients with PSC had a worse prognosis, with a median survival of 5 months (95% confidence interval [CI]: 5-6 months) and a 5-year OS rate of 15.3% (95% CI: 13.9%-16.9%). Similar outcomes were demonstrated after 1:1 PSM. Moreover, the competing risk model showed that age, T stage, M stage, tumor size, lymph node ratio (LNR), surgery, and chemotherapy were associated with PSC-specific mortality. The 5-year C-index of the nomogram was 0.718. Calibration curves illustrated that the nomogram was well-validated and had great accuracy. Conclusions: Patients with PSC had a worse survival outcome compared with SCC or LAC patients. Age, T stage, M stage, tumor size, LNR, surgery, and chemotherapy were associated with PSC-specific mortality. The competing risk nomogram displayed excellent discrimination in predicting PSC-specific mortality.

A case of PD-L1 negative advanced pulmonary sarcomatoid carcinoma effectively treated with atezolizumab, carboplatin, paclitaxel, and bevacizumab

Pulmonary sarcomatoid carcinoma (PSC) is an extremely rare neoplasm with poor prognosis and no established treatment. A 50-year-old man presented with fever, was found to have a mass measuring 14 cm in the right upper lobe of the chest, along with right pleural effusion on computed tomography (CT). Positron emission tomography-CT revealed abnormal tracer uptake in the area corresponding to the mass in the upper lobe. Hence, convex-probe endobronchial ultrasound-guided transbronchial needle aspiration was performed. Histological examination revealed dense proliferation of spindle tumor cells and no programmed death-ligand 1 (PD-L1) expression. Thus, he was diagnosed with PSC (cT4N0M1a, clinical stage IVA), and four-agent combination chemotherapy with atezolizumab, carboplatin, paclitaxel, and bevacizumab was initiated. Marked shrinkage of the mass and symptomatic improvements were observed following the treatment initiation. Tumor shrinkage was further noted after shifting to maintenance therapy with atezolizumab and bevacizumab; the patient exhibited no symptom exacerbation 2 years later and continued the treatment. Our case showed that four-agent combination chemotherapy with atezolizumab, carboplatin, paclitaxel, and bevacizumab could be an effective treatment option for advanced PSC with or without PD-L1 expression.

Sarcomatoid Mesothelioma: A Clinicopathological and Immunohistochemical Study of 64 Cases

Sixty-four cases of sarcomatoid pleural mesothelioma represent the basis of this study. The patients are 51 men and 13 women between the ages of 42 and 79 years, who presented with symptoms of chest pain, cough, and weight loss. Diagnostic imaging showed the presence of diffuse pleural thickening with encasement of the lung parenchyma in all the cases. All patients had surgical resection via extrapleural pneumonectomy. By immunohistochemistry, all cases were positive for cytokeratin AE1/AE3; however, reactivity with other markers including keratin 5/6, calretinin, and D2-40 was seen in different proportions, whereas a few cases showed positive staining for GATA3, WT1, and p40. All tumors were negative for carcinomatous epitopes (carcinoembryonic antigen, CD15, and TTF1). Our findings show that even though the use of immunohistochemical stains plays an important role in the final interpretation, the best results are accomplished by a global interpretation of clinical, radiographical, and immunohistochemical findings. It is also important to highlight that it does not seem to be a single immunohistochemical stain that is pathognomonic of sarcomatoid mesothelioma and that some other stains that are commonly used for other tumors may also show positive staining in a small percentage of sarcomatoid mesotheliomas.

Clinicopathological features and prognostic analysis of metastatic pulmonary sarcomatoid carcinoma: a SEER analysis

Background

Pulmonary sarcomatoid carcinoma (PSC) is a rare type of non-small cell lung cancer (NSCLC). Metastases are often detected at the first diagnosis. Despite high rates of distant metastasis, there is insufficient data describing the characteristics of PSC metastasis.

Methods

We performed a Surveillance, Epidemiology, and End Results (SEER) database-based analysis of clinicopathological features and prognosis of distant metastasis in PSC patients. Data queried for this analysis included PSC patients in the database between 2010 and 2016.

Results

A total of 934 patients met the criteria for inclusion in the analysis and included, at the time of diagnosis, 512 (54.8%) patients with metastasis, including bone (n=152; 16.3%), brain (n=108; 11.6%), liver (n=70; 7.5%), lung (n=142; 15.2%) metastases. Binary logistic regression showed that patients with giant cell carcinoma [odds ratio (OR) 4.023, 95% confidence interval (CI): 2.113-7.661, P<0.001] and spindle cell carcinoma (OR 3.151, 95% CI: 1.699-5.843, P<0.001) were associated with metastasis. Log-rank test and Kaplan-Meier plots indicated poor prognosis in metastatic patients [the 1-, 3-, and 5-year overall survival (OS) rates were 14.1%, 5.5%, and 4.8%, respectively]. Multivariable analysis showed younger and chemotherapy as improved prognostic factors of PSC patients with single metastasis site.

Conclusions

The SEER database-based analysis revealed the clinical features of distant metastasis of PSC and showed that different histological types posed distinct metastasis potential. Besides, age and chemotherapy were the independent prognostic factors of PSC patients with single metastasis site.

Additional chemotherapy improves survival in stage II-III pulmonary sarcomatoid carcinoma patients undergoing surgery: a propensity scoring matching analysis

Background

The role of additional chemotherapy in pulmonary sarcomatoid carcinoma (PSC) is controversial. This study aimed to investigate the function of chemotherapy in PSC patients with surgical resection.

Methods

PSC patient information between 2004 to 2016 was extracted from the Surveillance, Epidemiology, and End Results (SEER) database. X-tile software was used to calculate the optimal cut-off value to divide groups. The disease stages were recalculated according to the American Joint Commission on Cancer (AJCC) 8^th edition tumor-node-metastasis (TNM) staging system. Propensity score matching (PSM) analysis was conducted to balance the baseline of patients. Kaplan-Meier analysis and Cox proportional hazards analysis were used to evaluate survival outcome.

Results

A total of 865 PSC patients were included in our study. Among them, 611 patients were only operated with surgery, and the 254 others were treated with additional chemotherapy. The median age was 69.0 years (interquartile range, 61.6 to 76.3 years). Kaplan-Meier analysis showed that patients with additional chemotherapy had longer overall survival (OS) and cancer-specific survival (CSS, P<0.05). The median OS and the 1-, 3-, 5-year OS rates were 36.0 months (95% CI: 20.5–51.5 months), 72.7%, 49.6% and 38.5% in the chemotherapy group and 29.0 months (95% CI: 23.6–34.4 months), 63.2%, 44.5% and 37.6% in the non-chemotherapy group, respectively. The OS advantage of chemotherapy was not statistically significant after PSM analysis. Moreover, Cox proportional hazards model showed that chemotherapy was an independent prognosis factor for better OS and CSS. In subgroup of stages II and III, the chemotherapy group had a survival advantage (P<0.05). Patients with young age, female gender, low histology grade, large tumor size and lobectomy surgical resection benefited more from chemotherapy.

Conclusions

Chemotherapy is recommended for stages II and III PSC patients undergoing surgery, especially for those with young age, female gender, low histology grade, large tumor size and lobectomy surgical resection.

Genomic origin and intratumor heterogeneity revealed by sequencing on carcinomatous and sarcomatous components of pulmonary sarcomatoid carcinoma

Pulmonary sarcomatoid carcinoma (PSC) contains carcinomatous component (CaC) and sarcomatous component (SaC). Herein, we explored the genomic origin and intratumor heterogeneity (ITH) of PSC. We collected 31 resected PSC tumors and obtained CaC and SaC by laser capture microdissection for next-generation sequencing. The majority of PSCs (97%) had component-shared alterations. Driver mutations in EGFR, KRAS, MET, PIK3CA, and EML4-ALK fusion were mostly component-shared. Twenty-seven (87%) PSCs had component-private alterations. Compared with pure lung adenocarcinoma (LUAD), adenocarcinoma component of PSC showed lower EGFR incidence. Compared with other typical sarcomas, numerous genes of SaC exhibited significant differences. CaC and SaC had equivalent and proportional tumor mutation burden (TMB), as well as PD-L1 level. Compared with LUAD, SaC had significant higher TMB and more patients with high PD-L1 expression (tumor proportion score ≥50%). PSC with lower proportion of component-shared alterations (trunk-ratio) had a prolonged disease-free survival (DFS), regardless of the influence of clinical factors. We conclude that most PSCs originate from a monoclone accompanied by genomic ITH which is a potential independent prognostic factor, and more proportion of PSCs may be beneficial from immune checkpoint inhibitors.

The diagnostic utility of zinc E-box 1 (ZEB1) transcription factor for identification of pulmonary sarcomatoid carcinoma in cytologic and surgical specimens

OBJECTIVE

Although uncommon, pulmonary sarcomatoid carcinoma carries a worse prognosis due to poor chemotherapeutic response. Currently, a histologic spindle and/or giant cell component indicates sarcomatoid differentiation, with zinc E-box binding homeobox 1 (ZEB1) implicated in promoting epithelial-mesenchymal transition. However, diagnostic use of ZEB1 in limited specimens, including cell block (CB) preparations, remains unclear.

MATERIALS AND METHODS

Pulmonary sarcomatoid (SARC, n = 15), typical (TC, n = 10) and atypical carcinoid (AC, n = 10), small cell (SCLC, n = 8) and large cell neuroendocrine carcinoma (LCNEC, n = 9), squamous cell carcinoma (SQ, n = 7), and adenocarcinoma (ADC, n = 7) CBs along with 69 SARCs, 20 TCs, 21 ACs, 9 SCLCs, 10 LCNECs, 71 SQs, 402 ADCs, 16 large cell carcinoma (LCC) and 17 other thoracic tumor (OT) surgical specimens between 2007 and 2018 were retrieved. ZEB1 (Sigma Aldrich, St. Louis, Mo and Novus Biological, Centennial, Colo) immunohistochemistry was graded 1+ to 3+, with ≥1+ and >5% staining considered positive.

RESULTS

Nuclear ZEB1 was seen in 80% SARC (12/15), 0% TC (0/10), 0% AC (0/10), 12.5% SCLC (1/8) and 11.1% LCNEC (1/9), 0% SQ (0/7), and 0% ADC (0/7) CBs. In surgical specimens, 75.4% SARCs (52/69), 0% TCs (0/20), 0% ACs (0/21), 11.1% SCLCs (1/9), 30% LCNECs (3/10), 0% SQs (0/71), 0.2% ADCs (1/402), 12.5% LCCs (2/16), and 11.8% OTs (2/17) demonstrated ZEB1. ZEB1 sensitivity and specificity in cytology and surgical specimens were 80% and 96.1%, and 75.4% and 98.1%, respectively.

CONCLUSIONS

ZEB1 is sensitive and highly specific for pulmonary sarcomatoid carcinoma in limited cytologic and surgical specimens. Diagnostic pitfalls include high-grade neuroendocrine tumors and large cell carcinoma, which are resolvable by morphologic considerations.

Uncommon Types of Lung Carcinoma With Mixed Histology: Sarcomatoid Carcinoma, Adenosquamous Carcinoma, and Mucoepidermoid Carcinoma

CONTEXT

- Lung tumors are histologically heterogeneous, but classification of lung carcinoma has prognostic impact and increasingly, specific molecular correlates.

OBJECTIVE

- To update the gross, microscopic, and molecular pathology of unusual lung carcinomas to assure accurate classification. In entities with mixed histology, the recognition of specific features or rare patterns is critical to diagnosis. These diagnoses can identify tumors with aggressive clinical behavior, and diagnostic pitfalls can therefore result in underdiagnosis of these already rare entities. Incorrect classification of more indolent tumors into the more aggressive categories can also occur. In the area of molecular pathology, these unusual tumors have a specific spectrum of molecular alterations.

DATA SOURCES

- PubMed searches for lung and sarcomatoid carcinoma, pleomorphic carcinoma, blastoma, carcinosarcoma, and adenosquamous and mucoepidermoid carcinoma were undertaken and this information was integrated with clinical experience of the author.

CONCLUSIONS

- These uncommon carcinomas have specific clinicopathologic features, and attention to their gross and microscopic pathology leads to classification with important associated molecular findings.

Whole transcriptome targeted gene quantification provides new insights on pulmonary sarcomatoid carcinomas

Pulmonary sarcomatoid carcinomas (PSC) are a rare group of lung cancer with a median overall survival of 9–12 months. PSC are divided into five histotypes, challenging to diagnose and treat. The identification of PSC biomarkers is warranted, but PSC molecular profile remains to be defined. Herein, a targeted whole transcriptome analysis was performed on 14 PSC samples, evaluated also for the presence of the main oncogene mutations and rearrangements. PSC expression data were compared with transcriptome data of lung adenocarcinomas (LUAD) and squamous cell carcinomas (LUSC) from The Cancer Genome Atlas. Deregulated genes were used for pathway enrichment analysis; the most representative genes were tested by immunohistochemistry (IHC) in an independent cohort (30 PSC, 31 LUAD, 31 LUSC). All PSC cases were investigated for PD-L1 expression. Thirty-eight genes deregulated in PSC were identified, among these IGJ and SLMAP were confirmed by IHC. Moreover, Forkhead box signaling and Fanconi anemia pathways were specifically enriched in PSC. Finally, some PSC harboured alterations in genes targetable by tyrosine kinase inhibitors, as EGFR and MET. We provide a deep molecular characterization of PSC; the identification of specific molecular profiles, besides increasing our knowledge on PSC biology, might suggest new strategies to improve patients management.

Best Practices Recommendations for Diagnostic Immunohistochemistry in Lung Cancer

Since the 2015 WHO classification was introduced into clinical practice, immunohistochemistry (IHC) has figured prominently in lung cancer diagnosis. In addition to distinction of small cell versus non-small cell carcinoma, patients' treatment of choice is directly linked to histologic subtypes of non-small cell carcinoma, which pertains to IHC results, particularly for poorly differentiated tumors. The use of IHC has improved diagnostic accuracy in the classification of lung carcinoma, but the interpretation of IHC results remains challenging in some instances. Also, pathologists must be aware of many interpretation pitfalls, and the use of IHC should be efficient to spare the tissue for molecular testing. The International Association for the Study of Lung Cancer Pathology Committee received questions on practical application and interpretation of IHC in lung cancer diagnosis. After discussions in several International Association for the Study of Lung Cancer Pathology Committee meetings, the issues and caveats were summarized in terms of 11 key questions covering common and important diagnostic situations in a daily clinical practice with some relevant challenging queries. The questions cover topics such as the best IHC markers for distinguishing NSCLC subtypes, differences in thyroid transcription factor 1 clones, and the utility of IHC in diagnosing uncommon subtypes of lung cancer and distinguishing primary from metastatic tumors. This article provides answers and explanations for the key questions about the use of IHC in diagnosis of lung carcinoma, representing viewpoints of experts in thoracic pathology that should assist the community in the appropriate use of IHC in diagnostic pathology.

[Current Status of Diagnosis and Treatment of Pulmonary Sarcomatoid Carcinoma]

Pulmonary sarcomatoid carcinoma (PSC) is a rare, poorly differentiated, subtype of non-small cell lung carcinoma (NSCLC) and constitutes approximately 0.1% to 0.5% of all lung malignancies. PSC can be divided into five subtypes based on the 2015 World Health Organization (WHO) classification of lung tumors: pleomorphic carcinoma, spindle cell carcinoma, giant cell carcinoma, carcinosarcoma, and pulmonary blastoma. Some imaging characteristics can be found for PSC although no special symptoms. The accurate pathological diagnosis of PSC can be a significant challenge, which depends on pathology and immunohistochemistry. PSC should be managed similar to other NSCLC, surgical resection is the standard management for early stage cases, moreover, multimodal treatment should be considered. However, PSC is insensitive to radiotherapy and chemotherapy, and has high rate of local and metastatic recurrence and poor prognosis. With the development of molecular pathology, targeted therapy and immunotherapy may have broad prospects.
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Pulmonary Sarcomatoid Carcinomas: A Review

Pulmonary sarcomatoid carcinomas belong to a group of neoplasms that remain incompletely understood. They are rare tumors of the bronchopulmonary system that incorporate a wide range of neoplasms that by definition contain a sarcomatoid component characterized by spindle or giant cells. Such classification has led to a heterogenous tumor category that includes neoplasms with different clinical, morphologic, and prognostic features. To date, the histopathologic diagnosis of pulmonary sarcomatoid carcinomas does not require the use of ancillary testing and is based on light microscopic criteria alone. However, with recent advances in immunohistochemical and molecular methods, it is becoming increasingly clear that pulmonary sarcomatoid carcinomas represent poorly differentiated or "dedifferentiated" variants of conventional non-small cell carcinomas with similar immunophenotype and molecular signatures. This review summarizes the latest insights and concepts of these unusual tumors and outlines future directions with emphasis on tumor classification and patient management.