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

Large cell carcinoma of the lung: LDCT features and survival in screen-detected cases

PURPOSE

To investigate the early radiological features and survival of Large Cell Carcinoma (LCC) cases diagnosed in low-dose computed tomography (LDCT) screening trials.

METHODS

Two radiologists jointly reviewed the radiological features of screen-detected LCCs observed in NLST, ITALUNG, and LUSI trials between 2002 and 2016, comprising a total of 29,744 subjects who underwent 3-5 annual screening LDCT examinations. Survival or causes of death were established according to the mortality registries extending more than 12 years since randomization.

RESULTS

LCC was diagnosed in 30 (4 %) of 750 subjects with screen-detected lung cancer (LC), including 15 prevalent and 15 incident cases. Three additional LCCs occurred as interval cancers during the screening period. LDCT images were available for 29 cases of screen-detected LCCs, and 28 showed a single, peripheral, and well-defined solid nodule or mass with regularly smooth (39 %), lobulated (43 %), or spiculated (18 %) margins. One case presented as hilar mass. In 9 incident LCCs, smaller solid nodules were identified in prior LDCT examinations, allowing us to calculate a mean Volume Doubling Time (VDT) of 98.7 ± 47.8 days. The overall five-year survival rate was 50 %, with a significant (p = 0.0001) difference between stages I-II (75 % alive) and stages III-IV (10 % alive).

CONCLUSIONS

LCC is a fast-growing neoplasm that can escape detection by annual LDCT screening. LCC typically presents as a single solid peripheral nodule or mass, often with lobulated margins, and exhibits a short VDT. The 5-year survival reflects the stage at diagnosis.

Non-Small Cell Carcinoma-Not Otherwise Specified on Cytology Specimens in Patients with Solitary Pulmonary Lesion: Primary Lung Cancer or Metastatic Cancer?

Context:

Subtyping of solitary pulmonary lesion (SPL) in small amount of cytology specimen using a limited panel of immunohistochemistry (IHC) markers is very important to the correct choice of treatment. This study was performed to categorize non-small cell carcinoma-not otherwise specified (NSCC-NOS) on cytology in patients with SPL, especially with regard to the incidence of metastatic cancer.

Materials and Methods:

We reviewed 91 cases, in which a precise morphology-based, lineage-specific IHC-aided subtyping was not possible, that qualified as NSCC-NOS on cytology. A stepwise clinical approach and IHC of organ-specific markers was performed on each cell block (CB) to exclude metastasis from extrapulmonary malignancies.

Results:

Of the 91 evaluated cases, 65 (71.4%) were diagnosed as non-small cell lung carcinoma (NSCLC)-NOS, 24 (26.4%) were metastatic cancer, and the remaining 2 (2.2%) had undetermined diagnoses. The most frequent primary tumor site was the colorectum (41.7%), followed by breast (20.8%), kidney (8.3%), and then stomach, duodenum, liver, pancreas, gallbladder, prostate, and skin (4.2% each, 1 of 24). Moreover, we found that 7 of the 24 patients with metastatic cancer had a history of extrapulmonary malignancy that was unknown at the time of cytology-based diagnosis.

Conclusions:

These results underscored the need for accurate and stepwise clinical correlation to rule out the possibility of pulmonary metastasis from other sites and appropriate but judicious IHC (i.e., CDX2) on CB for SPL to increase refinement of the cytology diagnosis of NSCC-NOS.

Molecular Pathology of Primary Non-small Cell Lung Cancer

Lung carcinoma is one of the most common human cancers and is estimated to have an incidence of approximately 2 million new cases per year worldwide with a 20% mortality rate. Lung cancer represents one of the leading causes of cancer related death in the world. Of all cancer types to affect the pulmonary system, non-small cell lung carcinoma comprises approximately 80-85% of all tumors. In the past few decades cytogenetic and advanced molecular techniques have helped define the genomic landscape of lung cancer, and in the process, revolutionized the clinical management and treatment of patients with advanced non-small cell lung cancer. The discovery of specific, recurrent genetic abnormalities has led to the development of targeted therapies that have extended the life expectancy of patients who develop carcinoma of the lungs. Patients are now routinely treated with targeted therapies based on identifiable molecular alterations or other predictive biomarkers which has led to a revolution in the field of pulmonary pathology and oncology. Numerous different testing modalities, with various strengths and limitations now exist which complicate diagnostic algorithms, however recently emerging consensus guidelines and recommendations have begun to standardize the way to approach diagnostic testing of lung carcinoma. Herein we provide an overview of the molecular genetic landscape of non-small cell lung carcinoma, with attention to those clinically relevant alterations which drive management, as well as review current recommendations for molecular testing.

Clinical characteristics and prognosis of pulmonary large cell carcinoma: A population-based retrospective study using SEER data

BACKGROUND

Pulmonary large cell carcinoma (LCC) is an infrequent neoplasm with a poor prognosis. This study explored the clinical characteristics and survival prognostic factors of LCC patients.

METHODS

Patient data were extracted from the Surveillance, Epidemiology, and End Results (SEER) database. Chi-square tests or rank-sum tests were used to compare differences in clinical characteristics. Log-rank tests, univariate, and multivariate analyses were performed to investigate the independent factors of survival. Analyses of stage I-IV patients were performed to further explore the optimal treatment.

RESULTS

In total, 3197 LCC patients were included in this analysis. Compared with other non-small cell lung cancers (NSCLCs), there was a worse overall survival (OS) from LCC. LCC was more common in males, over age 60 and in the upper lobe. A total of 73.6% of patients were stage III/IV. The median OS of stage I-IV patients was 42 months, 22 months, 11 months, and three months, respectively. The elderly, males, later stage, and main bronchus location, or overlapping lesions were risk factors for survival prognosis. In stage I-III patients, treatment including surgery could significantly reduce the risk of death by 60% at least compared with no therapy. Surgery was still beneficial for stage IV patients, and the hazard ratio (HR) compared with no therapy was 0.462 (P = 0.001).

CONCLUSIONS

Our study concluded that LCC has unique clinical features, and that age, sex, primary site, stage, and treatment are significantly related to OS. Surgery based comprehensive treatments are effective for LCC.

KEY POINTS

Significant findings of the study In stage IV patients, chemotherapy or radiotherapy combined with surgery could further improve survival. When surgical resection involved more than one lobe, it may be beneficial for survival prognosis. What this study adds LCC patients were principally male and over age 60, with later stages and poor survival prognosis. Age, sex, stage, primary site and therapy are closely related to survival.

Philip T. Cagle, MD-Editor-in-Chief of the Archives of Pathology & Laboratory Medicine, 2005-2019

• The Archives of Pathology & Laboratory Medicine was first published in 1926 as a specialty journal of the American Medical Association. It became the official journal of the College of American Pathologists in 1995. Under the dynamic leadership of its most recent editor-in-chief, Philip T. Cagle, MD, the Archives has dramatically increased its impact factor and become the most widely read general pathology journal. Dr. Cagle has consistently added leading pathologists to the editorial board, and the collective expertise of these individuals is clearly evident in new, cutting-edge journal masthead sections. The Archives has featured innovative content in the field of digital pathology, including articles on the utilization of smart phones in pathology and the incorporation of whole-slide images and videos into the content of articles. During the current editorial board's tenure, special sections were introduced and have proven immensely popular with the journal's readership. As the Archives celebrates its 94th anniversary, its editorial board remains committed to providing insightful and relevant medical knowledge. The journal's open access Web site ( www.archivesofpathology.org ) allows the dissemination of this information to every corner of the globe at no expense to those who wish to expand their knowledge or improve their medical practice. Dr. Cagle, with support from the editorial board and journal staff, has worked tirelessly during his tenure as Archives editor-in-chief to greatly enhance the content of the journal and its stature within pathology and laboratory medicine.

Lung Cancer Pathology: Current Concepts

Lung cancer can be diagnosed based on histologic biopsy or cytologic specimens. The 2015 World Health Organization Classification of Lung Tumors addressed the diagnosis of lung cancer in resection specimens and in small biopsies and cytology specimens. For these small specimens, diagnostic terms and criteria are recommended. Targetable mutations such as EGFR and ALK rearrangements emphasize the importance of managing these small specimens for molecular testing.

Molecular and Morphological Profiling of Lung Cancer: A Foundation for "Next-Generation" Pathologists and Oncologists

The pathological diagnosis of lung cancer has largely been based on the morphological features observed microscopically. Recent innovations in molecular and genetic technology enable us to compare conventional histological classifications, protein expression status, and gene abnormalities. The introduction of The Cancer Genome Atlas (TCGA) project along with the widespread use of the next-generation sequencer (NGS) have facilitated access to enormous data regarding the molecular profiles of lung cancer. The World Health Organization classification of lung cancer, which was revised in 2015, is based on this progress in molecular pathology; moreover, immunohistochemistry has come to play a larger role in diagnosis. In this article, we focused on genetic and epigenetic abnormalities in non-small cell carcinoma (adenocarcinoma and squamous cell carcinoma), neuroendocrine tumor (including carcinoids, small cell carcinoma, and large cell neuroendocrine carcinoma), and carcinoma with rare histological subtypes. In addition, we summarize the therapeutic targeted reagents that are currently available and undergoing clinical trials. A good understanding of the morphological and molecular profiles will be necessary in routine practice when the NGS platform is widely used.

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.

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.

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.

Unravelling the Long Non-Coding RNA Profile of Undifferentiated Large Cell Lung Carcinoma

Undifferentiated large cell lung carcinoma (LCLC) accounts for 2.9-9% of total lung cancers. Recently, RNA-seq based studies have revealed major genomic aberrations in LCLC. In this study, we aim to identify long non-coding RNAs (LncRNAs) expression pattern specific to LCLC. The RNA-seq profile of LCLC and other non-small cell lung carcinoma (NSCLC) was downloaded from Gene Expression Omnibus (GEO) and analyzed. Using 10 LCLC samples, we found that 18% of all the annotated LncRNAs are expressed in LCLC samples. Among 1794 expressed LncRNAs, 11 were overexpressed and 14 were downregulated in LCLC compared to normal samples. Based on receiver operating characteristic (ROC) analysis, we showed that the top five differentially expressed LncRNAs were able to differentiate between LCLC and normal samples with high sensitivity and specificity. Guilt by association analysis using genes correlating with differentially expressed LncRNAs identified several cancer-associated pathways, suggesting the role of these deregulated LncRNA in LCLC biology. We also identified the LncRNA differentially expressed in LCLC compared to lung squamous carcinoma (LUSC) and Lung-adenocarcinoma (LUAD). We found that LCLC sample showed more deregulated LncRNA in LUSC than LUAD. Interestingly, LCLC had more downregulated LncRNA compared to LUAD and LUSC. Our study provides novel insight into LncRNA deregulation in LCLC. This study also finds tools to diagnose LCLC and differentiate LCLC with other Non-Small Cell Lung Cancer.

Whole Slide Imaging Versus Microscopy for Primary Diagnosis in Surgical Pathology: A Multicenter Blinded Randomized Noninferiority Study of 1992 Cases (Pivotal Study)

Most prior studies of primary diagnosis in surgical pathology using whole slide imaging (WSI) versus microscopy have focused on specific organ systems or included relatively few cases. The objective of this study was to demonstrate that WSI is noninferior to microscopy for primary diagnosis in surgical pathology. A blinded randomized noninferiority study was conducted across the entire range of surgical pathology cases (biopsies and resections, including hematoxylin and eosin, immunohistochemistry, and special stains) from 4 institutions using the original sign-out diagnosis (baseline diagnosis) as the reference standard. Cases were scanned, converted to WSI and randomized. Sixteen pathologists interpreted cases by microscopy or WSI, followed by a wash-out period of ≥4 weeks, after which cases were read by the same observers using the other modality. Major discordances were identified by an adjudication panel, and the differences between major discordance rates for both microscopy (against the reference standard) and WSI (against the reference standard) were calculated. A total of 1992 cases were included, resulting in 15,925 reads. The major discordance rate with the reference standard diagnosis was 4.9% for WSI and 4.6% for microscopy. The difference between major discordance rates for microscopy and WSI was 0.4% (95% confidence interval, -0.30% to 1.01%). The difference in major discordance rates for WSI and microscopy was highest in endocrine pathology (1.8%), neoplastic kidney pathology (1.5%), urinary bladder pathology (1.3%), and gynecologic pathology (1.2%). Detailed analysis of these cases revealed no instances where interpretation by WSI was consistently inaccurate compared with microscopy for multiple observers. We conclude that WSI is noninferior to microscopy for primary diagnosis in surgical pathology, including biopsies and resections stained with hematoxylin and eosin, immunohistochemistry and special stains. This conclusion is valid across a wide variety of organ systems and specimen types.

The Molecular Pathology of Lung Cancer

Advances in lung cancer genomics have revolutionized the diagnosis and treatment of this heterogeneous and clinically significant group of tumors. This article provides a broad overview of the most clinically relevant oncogenic alterations in common and rare lung tumors, with an emphasis on the pathologic correlates of the major oncogenic drivers, including EGFR, KRAS, ALK, and MET. Illustrations emphasize the morphologic diversity of lung adenocarcinoma, including genotype-phenotype correlations of genomic evolution in tumorigenesis. Molecular diagnostic approaches, including PCR-based testing, massively parallel sequencing, fluorescence in situ hybridization, and immunohistochemistry are reviewed.

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.

Impact of Recent Developments in Lung Cancer on the Practice of Pathology

Landmark events in the field of lung cancer in the past year have the potential to significantly alter the practice of pathology. Three key events are (1) approval of payment for low-dose computed tomography screening for lung cancer, (2) publication of an extensively revised World Health Organization classification of lung cancers, and (3) approval of immunohistochemistry based companion diagnostics by the US Food and Drug Administration. We briefly review these milestones in the context of their impact on the practice of pathology.

Educational Value of Digital Whole Slides Accompanying Published Online Pathology Journal Articles: A Multi-Institutional Study

CONTEXT

-Despite great interest in using whole slide imaging (WSI) in pathology practice and education, few pathology journals have published WSI pertinent to articles within their pages or as supplemental materials.

OBJECTIVE

-To evaluate whether there is measurable added educational value of including WSI in publications.

DESIGN

-Thirty-seven participants, 16 (43.3%), 15 (40.5%), and 6 (16.2%) junior pathology residents (postgraduate year 1-2), senior pathology residents (postgraduate year 3-4), and board-certified pathologists, respectively, read a sequence of 10 journal articles on a wide range of pathology topics. A randomized subgroup also reviewed the WSI published with the articles. Both groups completed a survey tool assessing recall of text-based content and of image-based material pertinent to the diseases but not present in the fixed published images.

RESULTS

-The group examining WSI had higher performance scores in 72% of image-based questions (36 of 50 questions) as compared with the non-WSI group. As an internal study control, the WSI group had higher performance scores in only 40% of text-based questions (6 of 15 questions). The WSI group had significantly better performance than the non-WSI group for image-based questions compared with text-based questions (P < .05, Fisher exact test).

CONCLUSION

-Our study provides supporting evidence that WSI offers enhanced value to the learner beyond the text and fixed images selected by the author. We strongly encourage more journals to incorporate WSI into their publications.

The 2015 World Health Organization Classification of Lung Tumors: Impact of Genetic, Clinical and Radiologic Advances Since the 2004 Classification

The 2015 World Health Organization (WHO) Classification of Tumors of the Lung, Pleura, Thymus and Heart has just been published with numerous important changes from the 2004 WHO classification. The most significant changes in this edition involve (1) use of immunohistochemistry throughout the classification, (2) a new emphasis on genetic studies, in particular, integration of molecular testing to help personalize treatment strategies for advanced lung cancer patients, (3) a new classification for small biopsies and cytology similar to that proposed in the 2011 Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society classification, (4) a completely different approach to lung adenocarcinoma as proposed by the 2011 Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society classification, (5) restricting the diagnosis of large cell carcinoma only to resected tumors that lack any clear morphologic or immunohistochemical differentiation with reclassification of the remaining former large cell carcinoma subtypes into different categories, (6) reclassifying squamous cell carcinomas into keratinizing, nonkeratinizing, and basaloid subtypes with the nonkeratinizing tumors requiring immunohistochemistry proof of squamous differentiation, (7) grouping of neuroendocrine tumors together in one category, (8) adding NUT carcinoma, (9) changing the term sclerosing hemangioma to sclerosing pneumocytoma, (10) changing the name hamartoma to "pulmonary hamartoma," (11) creating a group of PEComatous tumors that include (a) lymphangioleiomyomatosis, (b) PEComa, benign (with clear cell tumor as a variant) and

The Archives of Pathology & Laboratory Medicine: The Most Widely Read Pathology Journal Today

The Archives of Pathology & Laboratory Medicine was first published in 1926 as a subspecialty journal of the American Medical Association. It became the official journal of the College of American Pathologists in 1995. Under the dynamic leadership of its most recent editor-in-chief, Philip T. Cagle, MD, and his vibrant editorial board, the Archives has nearly doubled its impact factor and become the most widely read general pathology journal today. Dr Cagle has consistently added leading pathologists to the editorial board, and the collective expertise of these individuals is clearly evident in new, cutting-edge journal masthead sections. The Archives has featured innovative content in the field of digital pathology, including articles on the utilization of smart phones in pathology and incorporation of whole-slide images and videos into the content of articles. Special sections have characterized the Archives during the current editorial board's tenure and have proven immensely popular with the journal's readership. As the Archives celebrates its 90th anniversary, its editorial board remains committed to providing insightful and relevant medical knowledge. The journal's open access Web site ( www.archivesofpathology.org ) allows the dissemination of this knowledge to every corner of the globe at no expense to those who wish to be educated or improve their medical practice.

[Large cell carcinoma, lymphoepithelioma-like carcinoma, NUT carcinoma]

The diagnosis of large cell carcinoma can only be made on a sampled resected tumor and should not be applied to biopsies or cytology. In the 2015 WHO classification, the definition of large cell carcinoma is restricted to carcinomas both lacking morphological signs of glandular, squamous or neuroendocrine differentiation and exhibiting a null or unclear phenotype (TTF1-/p40 ou p63 ou CK5/6+ focally). These carcinomas have an adenocarcinoma molecular profile because they harbor a significant number of KRAS and BRAF mutations, a profile that is more similar to adenocarcinoma than squamous cell carcinoma. They also have a worse prognosis than the other types of non-small cell lung carcinoma. Many large cell carcinomas previously classified on morphological data alone are now reclassified in the adenocarcinoma and squamous cell carcinoma types, including immunohistochemical features. The other large cell carcinoma subtypes from the 2004 WHO classification, i.e. large cell neuroendocrine carcinoma and basaloid carcinoma, are grouped respectively with the other neuroendocrine tumors and squamous cell carcinomas. Clear cell and rhabdoid features are now considered as cytological variants that can occur in any histopathological subtype and not as distinct subtypes. Lymphoepithelioma-like carcinoma is moved to the group of other and unclassified carcinomas as NUT carcinoma.

Next-Generation Sequencing of a Cohort of Pulmonary Large Cell Carcinomas Reclassified by World Health Organization 2015 Criteria

CONTEXT

The classification of pulmonary large cell carcinoma has undergone a major revision with the recent World Health Organization (WHO) 2015 Classification. Many large cell carcinomas are now reassigned to either adenocarcinoma with solid pattern or nonkeratinizing squamous cell carcinoma based on immunopositivity for adenocarcinoma markers or squamous cell carcinoma markers, respectively. Large cell carcinomas that are negative for adenocarcinoma and squamous cell carcinoma immunomarkers are now classified as large cell carcinoma with null immunohistochemical features (LCC-N). Although a few studies investigated the mutation profile of large cell carcinomas grouped by immunostain profile before the publication of the new WHO classification, investigation of tumors previously diagnosed as large cell carcinoma and reclassified according to the 2015 WHO classification has not, to our knowledge, been reported.

OBJECTIVE

To determine the mutation profiles of pulmonary large cell carcinomas reclassified by WHO 2015 criteria.

DESIGN

Archival cases of non-small cell lung carcinoma with large cell carcinoma morphology (n = 17) were reclassified according to 2015 WHO criteria. To determine mutation profile, we employed Ion Torrent (Life Technologies, Carlsbad, California)-based next-generation sequencing (50 genes; more than 2800 mutations) in addition to real-time quantitative reverse transcription polymerase chain reaction for ALK translocation detection.

RESULTS

Two of 17 cases (12%) were reclassified as LCC-N, and both had mutations-BRAF D594N in one case and KRAS G12C in the other case. Seven of 17 cases (41%) were reclassified in the adenocarcinoma with solid pattern group, which showed one KRAS G12C and one EGFR E709K + G719C double mutation in addition to mutations in TP53. Eight of 17 cases (47%) were reclassified in the nonkeratinizing squamous cell carcinoma group, which showed mutations in PIK3CA, CDKN2A, and TP53. No ALK translocations or amplifications were detected.

CONCLUSIONS

The adenocarcinoma with solid pattern group showed mutations typical of adenocarcinoma, whereas the nonkeratinizing squamous cell carcinoma group showed mutations typical of squamous cell carcinoma. Both LCC-N cases had mutations associated with adenocarcinoma, supporting the hypothesis that LCC-N is related to adenocarcinoma.

The use of virtual microscopy and a wiki in pathology education: Tracking student use, involvement, and response

Background:

The pathology laboratory course at the New York College of Podiatric Medicine involves the use of Virtual Microscopy. The students can scan the whole slide, section by section, and zoom in or out.

Methods:

Using the advantages of digital pathology, the students can, in addition, access the slide collections from other medical schools and put up normal histology (control) slides side-by-side with the pathology. They can cut and paste and preserve the region of interest that they find. They can edit and annotate their slides. A wiki was created (http://pathlab2014.wikifoundry.com)for the Class of 2014. The students saved, edited and uploaded their slides. In the wiki format, other students could comment, further edit, and even delete the slides.

Results:

The students studied Basic Mechanisms and System Pathology. During this time, they saved, edited, shared, and uploaded their slides to the wiki. These were available in one full presentation and were also grouped into 16 albums. They were available to all. Student access was followed by Google analytics. At the end of the course, a questionnaire was distributed, assessing their impression of the wiki format and soliciting strengths and weaknesses.

Conclusions:

The use of a wiki has a number of important advantages in pathology education. It trains the students in the more sophisticated skills that they will use as professional pathologists or as clinicians: (1) Telepathology-it enables them to share slides and discuss observations. (2) Archiving and retrieval - It models the challenge faced by hospitals, diagnostic labs and physicians in maintaining a collection of slides in a form that is easily accessible. (3) Image analysis-familiarity with the wiki format allows them to jump easily to capturing and storing images found in the literature or in a pathologist's report. Experience with the use of a wiki in pathology education has been quite satisfactory from both the faculty and the student's point of view.

Large cell carcinoma of the lung: a tumor in search of an author. A clinically oriented critical reappraisal

Large cell carcinoma (LCC) is a merely descriptive term indicating a subtype of lung cancer with no specific features of small-cell lung cancer (SCLC), adenocarcinoma (ADC) or squamous cell carcinoma (SQC). This diagnosis is allowed on surgical specimens only, whereas its counterpart in biopsy/cytology samples is non-small-cell lung carcinoma (NSCLC), not otherwise specified (NOS). Although these two terms do not fulfill the same concept, they can be interchangeable synonyms at the clinical level, reflecting, in different ways, the inability to define a specific subtype. Immunohistochemistry (IHC), next generation sequencing (NGS) analysis and, historically, electron microscopy have been unveiling diverse cell differentiation lineages in LCC, resulting in LCC-favor ADC, LCC-favor SQC and LCC-favor large-cell neuroendocrine carcinoma (LCNEC), the latter hopefully to be included into the neuroendocrine tumor (NET) group in the future. Paradoxically, however, the interpretation issues of LCC/NSCLC-NOS are not diminishing, but even increasing albeight an accurate diagnosis is oncologically required and crucial. Also, rare LCC/NSCLC-NOS cases exhibiting null/unclear phenotype, are difficult to classify, and this terminology could be maintained for the sake of classification (basically these tumors are serendipitous ADC, as also confirmed by the lack of p40). In this review article, seven relevant issues to LCC have been addressed by using a question-answer methodology, with final key points discussing major interpretation issues. In conclusion, most LCC/NSCLC-NOS may be eventually re-classified and addressed by exploiting IHC and/or molecular testing to satisfy the criteria of precision medicine (the right drug, to the right patient, at the right time).

Association of IASLC/ATS/ERS Histologic Subtypes of Lung Adenocarcinoma With Epidermal Growth Factor Receptor Mutations in 320 Resected Cases

BACKGROUND

The relationships between the subtypes defined by the new international histologic classification of lung adenocarcinoma (IASLC/ATS/ERS) and epidermal growth factor receptor (EGFR) mutations were studied.

PATIENTS AND METHODS

We retrospectively reviewed 320 patients with lung adenocarcinoma (162 women, 158 men; mean age, 69 years) who had undergone complete resection, focusing on the new histologic subtypes and EGFR mutations. The clinical stage was IA in 196 patients, IB in 95, IIA in 10, IIB in 10, IIIA in 6, and IV in 3.

RESULTS

The most prevalent subtype was papillary (35.0%), followed by acinar (29.4%), lepidic (13.1%), solid (7.2%), adenocarcinoma in situ (6.6%), minimally invasive adenocarcinoma (6.3%), micropapillary (1.6%), and invasive mucinous adenocarcinoma (1.0%). These subtypes were predictive for both postoperative disease-free and overall survival. EGFR mutations, detected in 40.6% of all cases, were most frequent in acinar (48.4%), followed by minimally invasive adenocarcinoma (45.0%) and papillary (43.8%). They were least frequent in the solid subtype (17.4%). EGFR mutation status did not affect postoperative disease-free or overall survival.

CONCLUSION

The outcome after complete resection for lung adenocarcinoma was predicted by the proposed subtype classification. Because EGFR mutations were found in all subtypes, mutation analyses are essential to identify patients with postoperative relapse who would benefit from EGFR-tyrosine kinase inhibitor therapy.

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.

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.

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.