Large cell carcinoma of the lung: an endangered species?

Utility of Immunohistochemistry in the Diagnosis of Pleuropulmonary and Mediastinal Cancers: A Review and Update

CONTEXT.—

Immunohistochemistry has become a valuable ancillary tool for the accurate classification of pleuropulmonary and mediastinal neoplasms necessary for therapeutic decisions and predicting prognostic outcome. Diagnostic accuracy has significantly improved because of the continuous discoveries of tumor-associated biomarkers and the development of effective immunohistochemical panels.

OBJECTIVE.—

To increase the accuracy of diagnosis and classify pleuropulmonary neoplasms through immunohistochemistry.

DATA SOURCES.—

Literature review and the author's research data and personal practice experience.

CONCLUSIONS.—

This review article highlights that appropriately selecting immunohistochemical panels enables pathologists to effectively diagnose most primary pleuropulmonary neoplasms and differentiate primary lung tumors from a variety of metastatic tumors to the lung. Knowing the utilities and pitfalls of each tumor-associated biomarker is essential to avoid potential diagnostic errors.

Diagnostic Value of Insulinoma-Associated Protein 1 (INSM1) and Comparison With Established Neuroendocrine Markers in Pulmonary Cancers

CONTEXT.—

The diagnostic distinction of pulmonary neuroendocrine (NE) tumors from non-small cell lung carcinomas (NSCLCs) is clinically relevant for prognostication and treatment. Diagnosis is based on morphology and immunohistochemical staining.

OBJECTIVE.—

To determine the diagnostic value of insulinoma-associated protein 1 (INSM1), in comparison with established NE markers, in pulmonary tumors.

DESIGN.—

Fifty-four pulmonary NE tumors and 632 NSCLCs were stained for INSM1, CD56, chromogranin A, and synaptophysin. In a subset, gene expression data were available for analysis. Also, 419 metastases to the lungs were stained for INSM1. A literature search identified 39 additional studies with data on NE markers in lung cancers from the last 15 years. Seven of these included data on INSM1.

RESULTS.—

A positive INSM1 staining was seen in 39 of 54 NE tumors (72%) and 6 of 623 NSCLCs (1%). The corresponding numbers were 47 of 54 (87%) and 14 of 626 (2%) for CD56, 30 of 54 (56%) and 6 of 629 (1%) for chromogranin A, and 46 of 54 (85%) and 49 of 630 (8%) for synaptophysin, respectively. Analysis of literature data revealed that CD56 and INSM1 were the best markers for identification of high-grade NE pulmonary tumors when considering both sensitivity and specificity, while synaptophysin also showed good sensitivity. INSM1 gene expression was clearly associated with NE histology.

CONCLUSIONS.—

The solid data of both our and previous studies confirm the diagnostic value of INSM1 as a NE marker in pulmonary pathology. The combination of CD56 with INSM1 and/or synaptophysin should be the first-hand choice to confirm pulmonary high-grade NE tumors. INSM1 gene expression could be used to predict NE tumor histology.

Novel prognostic molecular markers in lung cancer

Lung carcinoma, especially in its most commonly diagnosed non-small cell histological form, is a challenge to diagnose and treat worldwide, due to the prognosis in patients with this type of cancer being poor and mortality rates being high. However, a number of patients with this type of lung carcinoma exhibit a longer than average overall survival. The specific molecular background of non-small-cell lung cancer that favors longer survival has not yet been determined. The aim of the current study was to review articles published in the years 2017-2018 and create a list of the most important and strongest non-conventional factors that could be used in the future assessment of the prognosis of patients with adenocarcinoma and squamous cell carcinoma of the lung who cannot undergo current targeted therapy. Analysis identified multiple prognostic factors in non-small cell lung carcinoma, including tumor mutational burden, which was revealed to be independent of the tumor stage or grade as well as other factors, including age, sex or targeted therapy effects. The selected molecular factors exhibit the potential to be used in the treatment of patients with specific problematic lung cancer, and may contribute to setting recommendations for the diagnosis, prognosis and treatment of individual patients with lung cancer.

Hyper-phosphorylation of Rb S249 together with CDK5R2/p39 overexpression are associated with impaired cell adhesion and epithelial-to-mesenchymal transition: Implications as a potential lung cancer grading and staging biomarker

Prediction of lung cancer metastasis relies on post-resection assessment of tumor histology, which is a severe limitation since only a minority of lung cancer patients are diagnosed with resectable disease. Therefore, characterization of metastasis-predicting biomarkers in pre-resection small biopsy specimens is urgently needed. Here we report a biomarker consisting of the phosphorylation of the retinoblastoma protein (Rb) on serine 249 combined with elevated p39 expression. This biomarker correlates with epithelial-to-mesenchymal transition traits in non-small cell lung carcinoma (NSCLC) cells. Immunohistochemistry staining of NSCLC tumor microarrays showed that strong phospho-Rb S249 staining positively correlated with tumor grade specifically in the squamous cell carcinoma (SCC) subtype. Strong immunoreactivity for p39 positively correlated with tumor stage, lymph node invasion, and distant metastases, also in SCC. Linear regression analyses showed that the combined scoring for phospho-Rb S249, p39 and E-cadherin in SCC is even more accurate at predicting tumor staging, relative to each score individually. We propose that combined immunohistochemistry staining of NSCLC samples for Rb phosphorylation on S249, p39, and E-cadherin protein expression could aid in the assessment of tumor staging and metastatic potential when tested in small primary tumor biopsies. The intense staining for phospho-Rb S249 that we observed in high grade SCC could also aid in the precise sub-classification of poorly differentiated SCCs.

A quantitative method for assessing smoke associated molecular damage in lung cancers

BACKGROUND

While tobacco exposure is the cause of the vast majority of lung cancers, an important percentage arise in lifetime never smokers. Documenting the precise extent of tobacco induced molecular changes may be of importance. Also, the contribution of environmental tobacco smoke (ETS) is difficult to assess.

METHODS

We developed and validated a quantitative method to assess the extent of tobacco related molecular damage by combing the most characteristic changes associated with tobacco smoke, the tumor mutation burden (TMB) and type of molecular changes present in lung cancers. Using maximum entropy (MaxEnt) as a classifier, we developed a F score. F score values >0 were considered to show evidence of tobacco related molecular damage, while values ≤0 were considered to lack evidence of tobacco related molecular damage. Compared to the stated patient tobacco exposure histories, the F scores had sensitivity, specificity and accuracy values of 85-87%. Using this method, we analyzed public data sets of lung adenocarcinoma (LUAD), lung squamous cell (LUSC) and small cell lung cancer (SCLC).

RESULTS

Less than 10% of LUSCs and SCLCs had negative F scores, while 27% to 35% of LUADs had positive scores. The F score showed a highly significant downward trend when LUADs were subdivided into the following categories: ever, reformed ≤15 years, reformed >15 years and never smokers. Most of the examined bronchial carcinoids (a lung cancer type not associated with smoke exposure) had negative F scores. In addition, most LUADs with EGFR mutations had negative F scores, while almost all with KRAS mutations had positive scores.

CONCLUSIONS

We have established and validated a quantitative assay that will be of use in assessing the presence and degree of smoke associated molecular damage in lung cancers arising in ever and never smokers.

Classification and Pathology of Lung Cancer

Advancement in the understanding of lung tumor biology enables continued refinement of lung cancer classification, reflected in the recently introduced 2015 World Health Organization classification of lung cancer. In small biopsy or cytology specimens, special emphasis is placed on separating adenocarcinomas from the other lung cancers to effectively select tumors for targeted molecular testing. In resection specimens, adenocarcinomas are further classified based on architectural pattern to delineate tissue types of prognostic significance. Neuroendocrine tumors are divided into typical carcinoid, atypical carcinoid, small cell carcinoma, and large cell neuroendocrine carcinoma based on a combination of features, especially tumor cell proliferation rate.

Gene Expression Profiling of Large Cell Lung Cancer Links Transcriptional Phenotypes to the New Histological WHO 2015 Classification

INTRODUCTION

Large cell lung cancer (LCLC) and large cell neuroendocrine carcinoma (LCNEC) constitute a small proportion of NSCLC. The WHO 2015 classification guidelines changed the definition of the debated histological subtype LCLC to be based on immunomarkers for adenocarcinoma and squamous cancer. We sought to determine whether these new guidelines also translate into the transcriptional landscape of lung cancer, and LCLC specifically.

METHODS

Gene expression profiling was performed by using Illumina V4 HT12 microarrays (Illumina, San Diego, CA) on samples from 159 cases (comprising all histological subtypes, including 10 classified as LCLC WHO 2015 and 14 classified as LCNEC according to the WHO 2015 guidelines), with complimentary mutational and immunohistochemical data. Derived transcriptional phenotypes were validated in 199 independent tumors, including six WHO 2015 LCLCs and five LCNECs.

RESULTS

Unsupervised analysis of gene expression data identified a phenotype comprising 90% of WHO 2015 LCLC tumors, with characteristics of poorly differentiated proliferative cancer, a 90% tumor protein p53 gene (TP53) mutation rate, and lack of well-known NSCLC oncogene driver alterations. Validation in independent data confirmed aggregation of WHO 2015 LCLCs in the specific phenotype. For LCNEC tumors, the unsupervised gene expression analysis suggested two different transcriptional patterns corresponding to a proposed genetic division of LCNEC tumors into SCLC-like and NSCLC-like cancer on the basis of TP53 and retinoblastoma 1 gene (RB1) alteration patterns.

CONCLUSIONS

Refined classification of LCLC has implications for diagnosis, prognostics, and therapy decisions. Our molecular analyses support the WHO 2015 classification of LCLC and LCNEC tumors, which herein follow different tumorigenic paths and can accordingly be stratified into different transcriptional subgroups, thus linking diagnostic immunohistochemical staining-driven classification with the transcriptional landscape of lung cancer.

The impact of immunohistochemistry on the classification of lung tumors

INTRODUCTION

To highlight the role of immunohistochemistry to lung cancer classification on the basis of existing guidelines and future perspectives.

AREAS COVERED

Four orienting key-issues were structured according to an extensive review on the English literature: a) cancer subtyping; b) best biomarkers and rules to follow; c) negative and positive profiling; d) suggestions towards an evidence-based proposal for lung cancer subtyping. A sparing material approach based on a limited number of specific markers is highly desirable. It includes p40 for squamous cell carcinoma ('no p40, no squamous'), TTF1 for adenocarcinoma, synaptophysin for neuroendocrine tumors and vimentin for sarcomatoid carcinoma. A close relationship between genotype and phenotype also supports a diagnostic role for negative profiles. Expert commentary: Highly specific and sensitive IHC markers according to positive and negative diagnostic algorithms seem appropriate for individual patients' lung cancer subtyping.

Clinicopathological features and prognosis of primary pulmonary lymphoepithelioma-like carcinoma

BACKGROUND

Lymphoepithelioma-like carcinoma (LELC) is a rare form of non-small cell lung carcinoma. The current study focused on its clinicopathological features and potential factors influencing the prognosis.

METHODS

The statistical analysis was based on the clinicopathological records and the prognosis of 43 LELC patients, analyzed by Kaplan-Meier method, Log-rank test, and COX regression analysis.

RESULTS

The patients' average age was 57.35±9.22 years, 86.05% of them were non-smokers and 53.49% were women. The average tumor diameter was 3.24±1.57 cm. The 2- and 5-year overall survival (OS) rates of LELC patients were 90% and 74%, respectively; the disease-free survival (DFS) rates were 87% and 47%, respectively. The patients with large tumor, accompanied with lymph nodes metastasis or at the advanced stage had the worst OS, and the patients with lymph nodes metastasis or at the advanced stage had the worst DFS. Univariate analysis indicated that T and N grading and TNM stage influenced the OS, and N grading and TNM stage influenced the DFS; the independent factors affecting OS or DFS were not identified by multivariate analysis.

CONCLUSIONS

LELC commonly occurred in senior non-smoking women. In summary, the prognosis of LELC was satisfactory.

Mutational and gene fusion analyses of primary large cell and large cell neuroendocrine lung cancer

Large cell carcinoma with or without neuroendocrine features (LCNEC and LC, respectively) constitutes 3-9% of non-small cell lung cancer but is poorly characterized at the molecular level. Herein we analyzed 41 LC and 32 LCNEC (including 15 previously reported cases) tumors using massive parallel sequencing for mutations in 26 cancer-related genes and gene fusions in ALK, RET, and ROS1. LC patients were additionally subdivided into three immunohistochemistry groups based on positive expression of TTF-1/Napsin A (adenocarcinoma-like, n = 24; 59%), CK5/P40 (squamous-like, n = 5; 12%), or no marker expression (marker-negative, n = 12; 29%). Most common alterations were TP53 (83%), KRAS (22%), MET (12%) mutations in LCs, and TP53 (88%), STK11 (16%), and PTEN (13%) mutations in LCNECs. In general, LCs showed more oncogene mutations compared to LCNECs. Immunomarker stratification of LC revealed oncogene mutations in 63% of adenocarcinoma-like cases, but only in 17% of marker-negative cases. Moreover, marker-negative LCs were associated with inferior overall survival compared with adenocarcinoma-like tumors (p = 0.007). No ALK, RET or ROS1 fusions were detected in LCs or LCNECs. Together, our molecular analyses support that LC and LCNEC tumors follow different tumorigenic paths and that LC may be stratified into molecular subgroups with potential implications for diagnosis, prognostics, and therapy decisions.

Oxidative stress associates with aggressiveness in lung large-cell carcinoma

Oxidative stress is involved in many cancer-related processes; however, current therapeutics are unable to benefit from this approach. The lungs have a very exquisite redox environment that may contribute to the frequent and deadly nature of lung cancer. Very few studies specifically address lung large-cell carcinoma (LCC), even though this is one of the major subtypes. Using bioinformatic (in silico) tools, we demonstrated that a more aggressive lung LCC cell line (HOP-92) has an overall increase activity of the human antioxidant gene (HAG) network (P = 0.0046) when compared to the less aggressive cell line H-460. Gene set enrichment analysis (GSEA) showed that the expression of metallothioneins (MT), glutathione peroxidase 1 (GPx-1), and catalase (CAT) are responsible for this difference in gene signature. This was validated in vitro, where HOP-92 showed a pro-oxidative imbalance, presenting higher antioxidant enzymes (superoxide dismutase (SOD), CAT, and GPx) activities, lower reduced sulfhydryl groups and antioxidant potential, and higher lipoperoxidation and reactive species production. Also, HAG network is upregulated in lung LCC patients with worst outcome. Finally, the prognostic value of genes enriched in the most aggressive cell line was assessed in this cohort. Isoforms of metallothioneins are associated with bad prognosis, while the thioredoxin-interacting protein (TXNIP) is associated with good prognosis. Thus, redox metabolism can be an important aspect in lung LCC aggressiveness and a possible therapeutic target.

Utility of Immunohistochemistry in the Diagnosis of Pleuropulmonary and Mediastinal Cancers: A Review and Update

Context

Immunohistochemistry has become an indispensable ancillary tool for the accurate classification of pleuropulmonary and mediastinal neoplasms necessary for therapeutic decisions and predicting prognostic outcome in the era of personalized medicine. Diagnostic accuracy has significantly improved because of the continuous discoveries of tumor-associated biomarkers and the development of effective immunohistochemical panels.

Objective

To increase the accuracy of diagnosis and classify pleuropulmonary neoplasms through immunohistochemistry.

Data Sources

Literature review, authors' research data, and personal practice experience.

Conclusions

This review article has shown that appropriately selecting immunohistochemical panels enables pathologists to effectively diagnose most primary pleuropulmonary neoplasms and differentiate primary lung tumors from a variety of metastatic tumors to the lung. The discovery of new mutation-specific antibodies identifying a subset of specific gene-arranged lung tumors provides a promising alternative and cost-effective approach to molecular testing. Knowing the utilities and pitfalls of each tumor-associated biomarker is essential to avoiding potential diagnostic errors.

A retrospective analysis of the clinicopathological characteristics of large cell carcinoma of the lung

The aim of the present study was to analyze and summarize the clinicopathological characteristics of large-cell lung carcinoma (LCLC) of the lung, in order to improve the definite diagnosis rate of LCLC. Clinicopathological data of 174 patients with LCLC, confirmed pathologically, were retrospectively reviewed. The 174 cases of LCLC accounted for 5.7% of the total lung cancer cases during the corresponding time period at the Affiliated Cancer Hospital of Tianjin Medical University (Tianjin, China), among which there were 131 males and 43 females with an average age of 61.4 years. The postoperative pathological diagnosis of the 174 cases showed 80 cases of classic LCLC, 64 cases of large cell neuroendocrine carcinoma (LCNEC), six cases of combined LCNEC, 19 cases of basaloid carcinoma, three cases of clear cell carcinoma and two cases of lymphoepithelioma-like carcinoma. Of the total 174 LCLC cases, 96 patients exhibited lymph node metastasis. LCLC is a highly aggressive malignancy with a high tendency of invasion and metastasis, although the incidence rate is low. A definite diagnosis of LCLC primarily relies on the pathological diagnosis. Each subtype of LCLC has its own pathomorphological and immunohistochemical characteristics.

Reproducibility of histopathological diagnosis in poorly differentiated NSCLC: an international multiobserver study

INTRODUCTION

The 2004 World Health Organization classification of lung cancer contained three major forms of non-small-cell lung cancer: squamous cell carcinoma (SqCC), adenocarcinoma (AdC), and large cell carcinoma. The goal of this study was first, to assess the reproducibility of a set of histopathological features for SqCC in relation to other poorly differentiated non-small-cell lung cancers and second, to assess the value of immunohistochemistry in improving the diagnosis.

METHODS

Resection specimens (n = 37) with SqCC, large cell carcinoma, basaloid carcinoma, sarcomatoid carcinoma, lymphoepithelial-like carcinoma, and solid AdC, were contributed by the participating pathologists. Hematoxylin and eosin (H&E) stained slides were digitized. The diagnoses were evaluated in two ways. First, the histological criteria were evaluated and the (differential) diagnosis on H&E alone was scored. Second, the added value of additional stains to make an integrated diagnosis was examined.

RESULTS

The histologic criteria defining SqCC were consistently used, but in poorly differentiated cases they were infrequently present, rendering the diagnosis more difficult. Kappa scores on H&E alone were for SqCC 0.46, large cell carcinoma 0.25, basaloid carcinoma 0.27, sarcomatoid carcinoma 0.52, lymphoepithelial-like carcinoma 0.56, and solid AdC 0.21. The κ score improved with the use of additional stains for SqCC (combined with basaloid carcinoma) to 0.57, for solid AdC to 0.63.

CONCLUSION

The histologic criteria that may be used in the differential diagnosis of poorly differentiated lung cancer were more precisely refined. Furthermore, additional stains improved the reproducibility of histological diagnosis of SqCC and AdC, uncovering information that was not present in routine H&E stained slides.

Treatment outcomes of patients with different subtypes of large cell carcinoma of the lung

BACKGROUND

Although large cell neuroendocrine carcinoma (LCNEC) and lymphoepithelioma-like carcinoma (LELC) are the variants of large cell carcinoma (LCC) of lung, there are few studies comparing them. The aim of this study was to compare the clinical characteristic and treatment outcomes of LCNEC, LELC, and classic LCC.

METHODS

Patients with LCNEC, LELC, or classic LCC were identified in a prospectively collected database, and their data were analyzed.

RESULTS

A total of 46 patients with classic LCC, 30 with LCNEC, and 18 with LELC, who received surgical resection with curative intent, were identified and included in the analysis. Patients with LELC were younger, and the frequency of nonsmokers was greater than in patients with classic LCC or LCNEC. In patients with LCNEC or LELC, most lesions were located on the left side. There were 5 surgical deaths, and the median follow-up time of the surviving patients was 44.1 months. The 5-year disease free survival among the three subgroups was similar (p = 0.601), but patients with LELC had a significantly better overall survival than the other two subgroups (LELC vs classic LCC, p = 0.009; LELC vs LCNEC, p = 0.002). Multivariate analysis showed tumor location site, tumor stage, and LELC were independent prognostic factors of overall survival.

CONCLUSIONS

The clinical manifestations and treatment outcomes of LCNEC, LELC, and classic LCC are different. LCNEC has a poor survival, and survival is not different than that of classic LCC. LELC is associated with younger age and a higher frequency of nonsmokers, and the treatment outcomes are better than those of other subtypes.

A genomics-based classification of human lung tumors

We characterized genome alterations in 1255 clinically annotated lung tumors of all histological subgroups to identify genetically defined and clinically relevant subtypes. More than 55% of all cases had at least one oncogenic genome alteration potentially amenable to specific therapeutic intervention, including several personalized treatment approaches that are already in clinical evaluation. Marked differences in the pattern of genomic alterations existed between and within histological subtypes, thus challenging the original histomorphological diagnosis. Immunohistochemical studies confirmed many of these reassigned subtypes. The reassignment eliminated almost all cases of large cell carcinomas, some of which had therapeutically relevant alterations. Prospective testing of our genomics-based diagnostic algorithm in 5145 lung cancer patients enabled a genome-based diagnosis in 3863 (75%) patients, confirmed the feasibility of rational reassignments of large cell lung cancer, and led to improvement in overall survival in patients with EGFR-mutant or ALK-rearranged cancers. Thus, our findings provide support for broad implementation of genome-based diagnosis of lung cancer.

Large cell carcinoma of lung: On the verge of extinction?

Pulmonary large cell carcinoma is a tumor whose existence as a defined entity has been challenged in recent years in the wake of advances in techniques to subtype lung cancer. Large cell carcinoma has been defined in the past as a tumor that lacks morphologic evidence of either glandular or squamous differentiation. This rather vague definition and the inclusion of more specific entities such as large cell neuroendocrine carcinoma, basaloid carcinoma, lymphoepithelioma-like carcinoma, clear cell carcinoma, and large cell carcinoma with rhabdoid phenotype as subtypes of large cell carcinoma has not only diluted the homogeneity of this entity but has also contributed to its use as a "wastebin" category for tumors lacking a definitive morphologic pattern. Today, there is increasing evidence that a large proportion of these tumors can be subtyped further using modern immunohistochemical and molecular methods. This is of special value not only from a diagnostic point of view but becomes increasingly important in terms of treatment choice since the selection of therapeutic modalities is often based on specific tumor histology. When viewed in this light, large cell carcinoma of the lung--as defined today--appears to be an outdated entity that needs to be reevaluated taking into account not only light microscopic findings but also the results of adjunct techniques such as immunohistochemistry and molecular profiling so that patients can benefit from more targeted therapies. This review examines the entity of pulmonary large cell carcinoma from these aspects and tries to delineate a practical diagnostic approach until further redefinition of this tumor is in place.

Does Immunohistochemistry Affect Response to Therapy and Survival of Inoperable Non–Small Cell Lung Carcinoma Patients? A Survey of 145 Stage III-IV Consecutive Cases

Whether non–small cell lung carcinoma (NSCLC) unveiled by immunohistochemistry (IHC) has the same clinical outcome as those typed by morphology is still matter of debate. A total of 145 stage III-IV, consecutive inoperable NSCLC patients treated by chemotherapy (133 cases) or EGFR tyrosine kinase inhibitor (12 cases) and including 100 biopsies, 11 surgical specimens, and 34 cytological samples had originally accounted for 120 adenocarcinomas (ADs), 19 squamous cell carcinomas (SQCs), and 6 adenosquamous carcinomas (ADSQCs) by integrating morphology and thyroid transcription factor-1 (TTF1)/p40 IHC. Thirty-two NSCLC–not otherwise specified (NSCLC-NOS) cases were identified by morphology revision of the original diagnoses, which showed solid growth pattern ( P < .001), 22 ADs, 5 SQCs, and 5 ADSQCs by IHC profiling ( P < .001), and 10 gene-altered tumors (3 EGFR, 5 KRAS, and 2 ALK). While no significant relationships were observed between response to therapy and original, morphology or IHC diagnoses, driver mutations and tumor differentiation by TTF1 expression, AD run better progression-free survival (PFS) or overall survival (OS) than other tumor types by morphology ( P = .010 and P = .047) and IHC ( P = .033 and P = .046), respectively. Furthermore, patients with NSCLC-NOS confirmed as AD by IHC tended to have poorer OS ( P = .179) and PFS ( P = .193) similar to that of ADSQC and SQC ( P = .702 and P = .540, respectively). A category of less differentiated AD with poorer prognosis on therapy could be identified by IHC, while there were no differences for SQC or ADSQC. The terminology of “NSCLC-NOS, favor by IHC” is appropriate to alert clinicians toward more aggressive tumors.

Large cell carcinoma of the lung: clinically oriented classification integrating immunohistochemistry and molecular biology

This study aimed at challenging pulmonary large cell carcinoma (LLC) as tumor entity and defining different subgroups according to immunohistochemical and molecular features. Expression of markers specific for glandular (TTF-1, napsin A, cytokeratin 7), squamous cell (p40, p63, cytokeratins 5/6, desmocollin-3), and neuroendocrine (chromogranin, synaptophysin, CD56) differentiation was studied in 121 LCC across their entire histological spectrum also using direct sequencing for epidermal growth factor receptor (EGFR) and v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) mutations and FISH analysis for ALK gene translocation. Survival was not investigated. All 47 large cell neuroendocrine carcinomas demonstrated a true neuroendocrine cell lineage, whereas all 24 basaloid and both 2 lymphoepithelioma-like carcinomas showed squamous cell markers. Eighteen out of 22 clear cell carcinomas had glandular differentiation, with KRAS mutations being present in 39 % of cases, whereas squamous cell differentiation was present in four cases. Eighteen out of 20 large cell carcinomas, not otherwise specified, had glandular differentiation upon immunohistochemistry, with an exon 21 L858R EGFR mutation in one (5 %) tumor, an exon 2 KRAS mutation in eight (40 %) tumors, and an ALK translocation in one (5 %) tumor, whereas two tumors positive for CK7 and CK5/6 and negative for all other markers were considered adenocarcinoma. All six LCC of rhabdoid type expressed TTF-1 and/or CK7, three of which also harbored KRAS mutations. When positive and negative immunohistochemical staining for these markers was combined, three subsets of LCC emerged exhibiting glandular, squamous, and neuroendocrine differentiation. Molecular alterations were restricted to tumors classified as adenocarcinoma. Stratifying LCC into specific categories using immunohistochemistry and molecular analysis may significantly impact on the choice of therapy.

Pulmonary large cell carcinoma lacking squamous differentiation is clinicopathologically indistinguishable from solid-subtype adenocarcinoma

CONTEXT

Pulmonary large cell carcinoma (LCC) includes tumors not readily diagnosed as adenocarcinoma (ADC) or squamous cell carcinoma on morphologic grounds, without regard to immunophenotype, according to the World Health Organization (WHO). This ambiguous designation may cause confusion over selection of mutation testing and directed therapies. Several groups have proposed the use of immunohistochemistry (IHC) to recategorize LCC as ADC or squamous cell carcinoma; however, it remains unclear if strictly defined LCCs are a clinicopathologically distinct lung tumor subset.

OBJECTIVE

To compare the pathologic, molecular, and clinical features of 2 morphologically similar tumors: solid-subtype ADC and LCC.

DESIGN

Tumors were included on the basis of solid growth pattern; tumors with squamous or neuroendocrine differentiation were excluded. Solid ADC (n = 42) and LCC (n = 57) were diagnosed by using WHO criteria (5 intracellular mucin droplets in ≥2 high-power fields for solid ADC) and tested for KRAS, EGFR, and ALK alterations.

RESULTS

Both solid ADC and LCC groups were dominated by tumors with "undifferentiated"-type morphology and both had a high frequency of thyroid transcription factor 1 expression. KRAS was mutated in 38% of solid ADCs versus 43% of LCCs (P = .62). One ALK-rearranged and 1 EGFR-mutated tumor were detected in the solid ADC and LCC groups, respectively. There were no significant differences in clinical features or outcomes; the prevalence of smoking in both groups was greater than 95%.

CONCLUSIONS

Other than a paucity of intracellular mucin, LCC lacking squamous or neuroendocrine differentiation is indistinguishable from solid-subtype ADC. We propose the reclassification of these tumors as mucin-poor solid adenocarcinomas.

Distinct profile of driver mutations and clinical features in immunomarker-defined subsets of pulmonary large-cell carcinoma

Pulmonary large-cell carcinoma-a diagnostically and clinically controversial entity-is defined as a non-small-cell carcinoma lacking morphologic differentiation of either adenocarcinoma or squamous cell carcinoma, but suspected to represent an end stage of poor differentiation of these tumor types. Given the recent advances in immunohistochemistry to distinguish adenocarcinoma and squamous cell carcinoma, and the recent insights that several therapeutically relevant genetic alterations are distributed differentially in these tumors, we hypothesized that immunophenotyping may stratify large-cell carcinomas into subsets with distinct profiles of targetable driver mutations. We therefore analyzed 102 large-cell carcinomas by immunohistochemistry for TTF-1 and ΔNp63/p40 as classifiers for adenocarcinoma and squamous cell carcinoma, respectively, and correlated the resulting subtypes with nine therapeutically relevant genetic alterations characteristic of adenocarcinoma (EGFR, KRAS, BRAF, MAP2K1/MEK1, NRAS, ERBB2/HER2 mutations and ALK rearrangements) or more common in squamous cell carcinoma (PIK3CA and AKT1 mutations). The immunomarkers classified large-cell carcinomas as variants of adenocarcinoma (n=62; 60%), squamous cell carcinoma (n=20; 20%) or marker-null (n=20; 20%). Genetic alterations were found in 38 cases (37%), including EGFR (n=1), KRAS (n=30), BRAF (n=2), MAP2K1 (n=1), ALK (n=3) and PIK3CA (n=1). All molecular alterations characteristic of adenocarcinoma occurred in tumors with immunoprofiles of adenocarcinoma or marker-null, but not in tumors with squamous immunoprofiles (combined mutation rate 50% vs 30% vs 0%, respectively; P<0.001), whereas the sole PIK3CA mutation occurred in a tumor with squamous profile (5%). Furthermore, marker-null large-cell carcinomas were associated with significantly inferior disease-free (P<0.001) and overall (P=0.001) survival. In conclusion, the majority (80%) of large-cell carcinomas can be classified by immunomarkers as variants of adenocarcinoma or squamous cell carcinoma, which stratifies these tumors into subsets with a distinct distribution of driver mutations and distinct prognoses. These findings have practical implications for diagnosis, predictive molecular testing and therapy selection.

ΔNp63 (p40) distribution inside lung cancer: a driver biomarker approach to tumor characterization

ΔNp63 (henceforth simply p40) is a squamous/basal-type biomarker corresponding to nontransactivating (non-TA) isoforms of p63 gene. Its prospective relevance as driver biomarker in lung cancer has not yet been thoroughly investigated. In all, 72 adenocarcinomas (ADs), 27 squamous cell carcinomas (SQCs), 13 pleomorphic carcinomas (PLCs), 10 small-cell lung carcinomas (SCLCs), 5 large-cell neuroendocrine carcinomas (LCNECs), 5 adenosquamous carcinomas (ADSQCs), 3 large-cell carcinomas with basaloid features (B-LCC), 2 carcinoids, 2 carcinosarcomas (CS), 2 salivary-gland type tumors (SGTTs) of the lung, and 5 pleural malignant epithelioid mesotheliomas (MEMs) were prospectively diagnosed by morphology and verified by immunohistochemistry for p40, p63, and thyroid transcription factor 1 (TTF1). Histological scores (HS) were devised by multiplying the percentage of immunoreactive cells (0 to 100%) by immunostaining intensity (low = 1 vs strong = 2, according to internal controls). There was a nonrandom distribution of p40 across the diverse tumor groups and cell differentiation lineages, with p40-HS > 100 closely paralleling squamous or myoepithelial carcinomas (SQC, B-LCC, SQC-containing PLC, ADSQC with predominant SQC, SGTT), and p40-HS ≤ 10 pinpointing AD, AD-containing PLC, or CS and neuroendocrine (NE) tumors. At variance, p63-HS was significantly higher than p40 in AD (P < .0001) and NE tumors (P = .0156), with positive predictive value being 83% and 95% and overall accuracy being 95% and 99%, respectively. Also, TTF1 was shared by gland-differentiated and NE tumors. MEM cases were always negative for all biomarkers. The HS-guided assessment of p40 allowed an effective orientation among thoracic malignancies at the level of individual tumor patients thereby contributing to prospectively realize a driver, holistic approach to cancer characterization.

Negative NKX2-1 (TTF-1) as temporary surrogate marker for treatment selection during EGFR-mutation analysis in patients with non-small-cell lung cancer

INTRODUCTION

In the past decade, major progress has been made toward personalized medical treatment of non-small-cell lung cancer (NSCLC) through the discovery of epithelial growth factor receptor (EGFR) mutations. However, mutation analysis takes extra time and additional costs in the diagnostic evaluation of lung cancer patients. It has been hypothesized that EGFR mutations are restricted to terminal respiratory unit -type adenocarcinoma expressing thyroid transcription factor-1 (official symbol NKX2-1) as determined by immunohistochemistry. The aim of the current study is to evaluate the potential of NKX2-1 immunohistochemistry as a prescreening test for EGFR mutation analysis.

METHODS

From 2004 to December 2010, 810 consecutive NSCLC tumor specimens were tested for EGFR mutations in a routine diagnostic procedure. Immunohistochemistry for NKX2-1 was performed (clone 8G7G3/1 [Dako]) and the results were compared with tumor EGFR-mutation status and clinicopathological characteristics.

RESULTS

EGFR mutations were detected in 114 specimens (14%). NKX2-1 expression was present in 68%. In the cases with EGFR mutation, NKX2-1 staining was positive in 92%. NKX2-1 immunohistochemical (IHC) staining was significantly associated with the presence of EGFR mutations (p = 5.3×10). NKX2-1 increased the negative predictive value in NSCLC to more than 95%.

CONCLUSIONS

In case of a negative NKX2-1 IHC staining, and only if clinically urgent, the high negative predictive value of more than 95% for EGFR mutations is a suitable temporary surrogate marker for the choice of starting with chemotherapy. In case of positive NKX2-1 IHC, the best strategy is to wait for the outcome of EGFR-mutation analysis and then choose the appropriate treatment.

The evolving role of the pathologist in the management of lung cancer

Major advances in pathology, molecular biology, patient diagnosis and care, as well as the advent of personalized therapy, have resulted in a greatly increased role for the pathologist, who has emerged as a key member of the lung cancer management team. A new multidisciplinary, clinically relevant classification of pulmonary adenocarcinoma has resulted in a paradigm shift in how we view and practice lung cancer pathology. In the future, the role of the pathologist will continue to grow and become fully integrated with clinical care.

ΔNp63 (p40) and thyroid transcription factor-1 immunoreactivity on small biopsies or cellblocks for typing non-small cell lung cancer: a novel two-hit, sparing-material approach

INTRODUCTION

Diagnosing non-small cell lung cancer on biopsy/cellblock samples by morphology may be demanding. As sparing material for molecular testing is mandatory, a minimalist immunohistochemistry (IHC)-based diagnostic approach is warranted by means of novel, reliable, and easy-to-assess biomarkers.

METHODS

Forty-six consecutive biopsy/cellblock samples and the corresponding resection specimens (as the gold standard for morphology and IHC) from 30 adenocarcinomas (AD), 10 squamous carcinomas (SQC), 5 adenosquamous carcinomas (ADSQC), and 1 sarcomatoid carcinoma (SC) were IHC-evaluated for p40 [corresponding to nontransactivating ΔNp63 isoforms] and thyroid transcription factor-1 (TTF1) by semiquantitative assessment. For p40, also immunodecoration intensity was taken into account and dichotomized as strong or low.

RESULTS

Nonrandom and overlapping distributions of the relevant markers were found in biopsy/cellblock and surgical specimens, which closely correlated with each other and the diverse tumor categories, with no differences in area under curve-receiver-operating-characteristic curves for each marker between any two samples, including p40 and p63. Diagnostic combinations were p40-/TTF1+ or TTF1- for AD (where p40 was negative, apart from 5/30 AD showing at the best 1-2% tumor cells with low intensity); p40+/TTF1- (p40 strong and by far higher than 50%) for SQC; and p40+/TTF1+ or p40+/TTF1- (p40 strong and less than 50%) for ADSQC. The single SC case was p40-/TTF1-, suggesting glandular lineage. Practically, 41/46 (89%) tumors were correctly classified by IHC on small samples, including 30 AD, 10 SQC, 1/5 ADSQC, and no SC. Underdiagnosis of ADSQC was actually because of sampling error of biopsies/cellblocks rather than insufficient biomarker robustness, whereas underdiagnosis of SC was really because of the failure of either marker to highlight epithelial-mesenchymal transition.

CONCLUSIONS

This minimalist IHC-based model of p40 and TTF1 on biopsy/cellblock samples was effective to correctly subtype most cases of lung cancer.

The challenge of NSCLC diagnosis and predictive analysis on small samples. Practical approach of a working group

Until recently, the division of pulmonary carcinomas into small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC) was adequate for therapy selection. Due to the emergence of new treatment options subtyping of NSCLC and predictive testing have become mandatory. A practical approach to the new requirements involving interaction between pulmonologist, oncologist and molecular pathology to optimize patient care is described. The diagnosis of lung cancer involves (i) the identification and complete classification of malignancy, (ii) immunohistochemistry is used to predict the likely NSCLC subtype (squamous cell vs. adenocarcinoma), as in small diagnostic samples specific subtyping is frequently on morphological grounds alone not feasible (NSCLC-NOS), (iii) molecular testing. To allow the extended diagnostic and predictive examination (i) tissue sampling should be maximized whenever feasible and deemed clinically safe, reducing the need for re-biopsy for additional studies and (ii) tissue handling, processing and sectioning should be optimized. Complex diagnostic algorithms are emerging, which will require close dialogue and understanding between pulmonologists and others who are closely involved in tissue acquisition, pathologists and oncologists who will ultimately, with the patient, make treatment decisions. Personalized medicine not only means the choice of treatment tailored to the individual patient, but also reflects the need to consider how investigative and diagnostic strategies must also be planned according to individual tumour characteristics.

Heterogeneity of large cell carcinoma of the lung: an immunophenotypic and miRNA-based analysis

Large cell carcinomas (LCCs) of the lung are heterogeneous and may be of different cell lineages. We analyzed 56 surgically resected lung tumors classified as LCC on the basis of pure morphologic grounds, using a panel of immunophenotypic markers (adenocarcinoma [ADC]-specific, thyroid transcription factor-1, cytokeratin 7, and napsin A; squamous cell carcinoma [SQCC]-specific, p63, cytokeratin 5, desmocollin 3, and Δnp63) and the quantitative analysis of microRNA-205 (microRNA sample score [mRSS]). Based on immunoprofiles 19 (34%) of the cases were reclassified as ADC and 14 (25%) as SQCC; 23 (41%) of the cases were unclassifiable. Of these 23 cases, 18 were classified as ADC and 5 as SQCC according to the mRSS. Our data show that an extended panel of immunohistochemical markers can reclassify around 60% of LCCs as ADC or SQCC. However, a relevant percentage of LCCs may escape convincing immunohistochemical classification, and mRSS could be used for further typing, but its clinical relevance needs further confirmation.

Immunohistochemical algorithm for differentiation of lung adenocarcinoma and squamous cell carcinoma based on large series of whole-tissue sections with validation in small specimens

Immunohistochemistry is increasingly utilized to differentiate lung adenocarcinoma and squamous cell carcinoma. However, detailed analysis of coexpression profiles of commonly used markers in large series of whole-tissue sections is lacking. Furthermore, the optimal diagnostic algorithm, particularly the minimal-marker combination, is not firmly established. We therefore studied whole-tissue sections of resected adenocarcinoma and squamous cell carcinoma (n=315) with markers commonly used to identify adenocarcinoma (TTF-1) and squamous cell carcinoma (p63, CK5/6, 34βE12), and prospectively validated the devised algorithm in morphologically unclassifiable small biopsy/cytology specimens (n=38). Analysis of whole-tissue sections showed that squamous cell carcinoma had a highly consistent immunoprofile (TTF-1-negative and p63/CK5/6/34βE12-diffuse) with only rare variation. In contrast, adenocarcinoma showed significant immunoheterogenetity for all 'squamous markers' (p63 (32%), CK5/6 (18%), 34βE12 (82%)) and TTF-1 (89%). As a single marker, only diffuse TTF-1 was specific for adenocarcinoma whereas none of the 'squamous markers,' even if diffuse, were entirely specific for squamous cell carcinoma. In contrast, coexpression profiles of TTF-1/p63 had only minimal overlap between adenocarcinoma and squamous cell carcinoma, and there was no overlap if CK5/6 was added as a third marker. An algorithm was devised in which TTF-1/p63 were used as the first-line panel, and CK5/6 was added for rare indeterminate cases. Prospective validation of this algorithm in small specimens showed 100% accuracy of adenocarcinoma vs squamous cell carcinoma prediction as determined by subsequent resection. In conclusion, although reactivity for 'squamous markers' is common in lung adenocarcinoma, a two-marker panel of TTF-1/p63 is sufficient for subtyping of the majority of tumors as adenocarcinomas vs squamous cell carcinoma, and addition of CK5/6 is needed in only a small subset of cases. This simple algorithm achieves excellent accuracy in small specimens while conserving the tissue for potential predictive marker testing, which is now an essential consideration in advanced lung cancer specimens.

Suitability of thoracic cytology for new therapeutic paradigms in non-small cell lung carcinoma: high accuracy of tumor subtyping and feasibility of EGFR and KRAS molecular testing

INTRODUCTION

The two essential requirements for pathologic specimens in the era of personalized therapies for non-small cell lung carcinoma (NSCLC) are accurate subtyping as adenocarcinoma (ADC) versus squamous cell carcinoma (SqCC) and suitability for EGFR and KRAS molecular testing. The aim of this study was to comprehensively review the performance of cytologic specimens for the above two goals in a high-volume clinical practice.

METHODS

Subtyping of primary lung carcinomas by preoperative cytology was correlated with subsequent resection diagnoses during a 1-year period (n = 192). The contribution of various clinicopathologic parameters to subtyping accuracy and utilization of immunohistochemistry (IHC) for NSCLC subtyping were analyzed. In addition, the performance of cytologic specimens submitted for EGFR/KRAS molecular testing during a 1-year period (n = 128) was reviewed.

RESULTS

Of the 192 preoperative cytology diagnoses, tumor subtype was definitive versus favored versus unclassified in 169 (88%) versus 15 (8%) versus 8 (4%) cases, respectively. Overall accuracy of cytologic tumor subtyping (concordance with histology) was 93% and accuracy of definitive diagnoses 96%. For a group of patients with ADC and SqCC (n = 165), the rate of unclassified cytologic diagnoses was 3% and overall accuracy 96%. IHC was used for subtyping of 9% of those cases, yielding 100% accuracy. The strongest predictors of difficulty in subtyping of ADC and SqCC were poor differentiation (p = 0.0004), low specimen cellularity (p = 0.019), and squamous histology (p = 0.003). Of 128 cytologic specimens submitted for molecular testing, 126 (98%) were suitable for analysis, revealing EGFR and KRAS mutations in 31 (25%) and 25 (20%) cases, respectively.

CONCLUSIONS

Cytologic subtyping of NSCLC is feasible and accurate, particularly when morphologic assessment is combined with IHC. Furthermore, routine cytologic specimens can be successfully used for EGFR/KRAS mutation analysis. Our data strongly support the suitability of cytologic specimens for the new therapeutic paradigms in NSCLC.

Large cell lung carcinoma with rhabdoid phenotype: Case report

Large cell carcinoma of the lung with a rhabdoid phenotype is very rare. We report a 62-year-old male patient admitted to our hospital due to chest pains and hemoptysis. The computed tomography scan of the lungs revealed a massive consolidation of the parenchyma in the upper right lobe. The right upper lobectomy and mediastinal lymph node sampling were carried out. The microscopic appearance suggested a large cell carcinoma with a rhabdoid phenotype, with no foci of any other carcinomatous components. The tumor cells had eosinophilic cytoplasmic globules and eccentric nuclei. Immunohistochemically, vimentin was diffusely positive. The epithelial membrane antigen and neuron-specific enolase were focally positive. We expect a good outcome for this patient because the diagnostic procedure and successful operation were performed in the early stage (IA-T1aN0) of the disease.