TTF1 expression in normal lung neuroendocrine cells and related tumors: immunohistochemical study comparing two different monoclonal antibodies

Patterns of Immunoreactivity with TTF-1 Antibodies 8G7G3/1 and SPT24 Suggest Distinct Immunoprofiles Between Most Pulmonary and Nonpulmonary Small Cell Carcinomas

Introduction. Small cell carcinoma can arise from various sites. Herein, we analyze the ability of 2 thyroid transcription factor-1 (TTF-1) antibodies (SPT24 and 8G7G3/1) to separate pulmonary from nonpulmonary small cell carcinoma. Materials and Methods. We analyzed 26 pulmonary and 83 nonpulmonary small cell carcinomas, and 14 Merkel cell carcinomas. Each tumor was stained with SPT24 and 8G7G3/1. Extent of nuclear staining was scored as diffuse (>50%), focal (11%-50%), rare (1%-10%), or negative (<1%). Results. All pulmonary small cell carcinomas were positive for SPT24 and 8G7G3/1. Four Merkel cell carcinomas (29%) were positive for SPT24 (ranging from rare-to-diffuse), while 2 (14%) showed rare expression with 8G7G3/1. For nonpulmonary small cell carcinomas, 69 (83%) were positive for SPT24 and 40 (48%) were positive for 8G7G3/1. For SPT24 positive tumors, the extent of 8G7G3/1 expression was equal in 17 (25%) and less in 52 tumors (75%), including 29 (42%) that were negative for 8G7G3/1. No nonpulmonary small cell carcinoma had more staining with 8G7G3/1 compared to SPT24. The differences in staining between 8G7G3/1 and SPT24 in the nonpulmonary cohort were statistically significant (P < 0.0001) with no significant difference between primary and metastatic lesions for 8G7G3/1 (P  =  0.66) or SPT24 (P  =  0.77). Conclusion. Most pulmonary small cell carcinomas are diffusely positive for both SPT24 and 8G7G3/1, whereas most nonpulmonary small cell carcinomas exhibit focal-to-no staining with 8G7G3/1 and significantly less staining with 8G7G3/1 compared to SPT24. However, these trends are not absolute and should be interpreted in conjunction with clinical and radiological findings.

Renal neuroendocrine tumors: clinical and molecular pathology with an emphasis on frequent association with ectopic Cushing syndrome

Renal neuroendocrine tumors (RenNETs) are rare malignancies with largely unknown biology, hormone expression, and genetic abnormalities. This study aims to improve our understanding of the RenNETs with emphasis of functional, hormonal, and genetic features. Surgically resected RenNETs (N = 13) were retrieved, and immunohistochemistry and next-generation sequencing (NGS) were performed in all cases. In addition, all published RenNETs were systematically reviewed. Our cohort (4 men and 9 women, mean age 42, mean tumor size 7.6 cm) included 2 patients with Cushing syndrome (CS). WHO grade (23% G1, 54% G2, and 23% G3) and tumor progression did not correlate. CS-associated RenNETs (CS-RenNETs) showed a solid and eosinophilic histology and stained for ACTH, while the remaining non-functioning tumors had a trabecular pattern and expressed variably hormones somatostatin (91%), pancreatic polypeptide (63%), glucagon (54%), and serotonin (18%). The transcription factors ISL1 and SATB2 were expressed in all non-functioning, but not in CS-RenNETs. NGS revealed no pathogenic alterations or gene fusions. In the literature review (N = 194), 15 (8%) of the patients had hormonal syndromes, in which CS being the most frequent (7/15). Large tumor size and presence of metastasis were associated with shorter patients' survival (p < 0.01). RenNETs present as large tumors with metastases. CS-RenNETs differ through ACTH production and solid-eosinophilic histology from the non-functioning trabecular RenNETs that produce pancreas-related hormones and express ISL1 and SATB2. MEN1 or DAXX/ARTX abnormalities and fusion genes are not detected in RenNETs, indicating a distinct yet unknown molecular pathogenesis.

The Apoptosis Inhibitor Protein Survivin Is a Critical Cytoprotective Resistor against Silica-Based Nanotoxicity

Exposure to nanoparticles is inevitable as they become widely used in industry, cosmetics, and foods. However, knowledge of their (patho)physiological effects on biological entry routes of the human body and their underlying molecular mechanisms is still fragmented. Here, we examined the molecular effects of amorphous silica nanoparticles (aSiNPs) on cell lines mimicking the alveolar-capillary barrier of the lung. After state-of-the-art characterization of the used aSiNPs and the cell model, we performed cell viability-based assays and a protein analysis to determine the aSiNP-induced cell toxicity and underlying signaling mechanisms. We revealed that aSiNPs induce apoptosis in a dose-, time-, and size-dependent manner. aSiNP-induced toxicity involves the inhibition of pro-survival pathways, such as PI3K/AKT and ERK signaling, correlating with reduced expression of the anti-apoptotic protein Survivin on the protein and transcriptional levels. Furthermore, induced Survivin overexpression mediated resistance against aSiNP-toxicity. Thus, we present the first experimental evidence suggesting Survivin as a critical cytoprotective resistor against silica-based nanotoxicity, which may also play a role in responses to other NPs. Although Survivin's relevance as a biomarker for nanotoxicity needs to be demonstrated in vivo, our data give general impetus to investigate the pharmacological modulation of Survivin`s functions to attenuate the harmful effects of acute or chronic inhalative NP exposure.

Transcriptional Circuitry of NKX2-1 and SOX1 Defines an Unrecognized Lineage Subtype of Small-Cell Lung Cancer

Rationale: The current molecular classification of small-cell lung cancer (SCLC) on the basis of the expression of four lineage transcription factors still leaves its major subtype SCLC-A as a heterogeneous group, necessitating more precise characterization of lineage subclasses. Objectives: To refine the current SCLC classification with epigenomic profiles and to identify features of the redefined SCLC subtypes. Methods: We performed unsupervised clustering of epigenomic profiles on 25 SCLC cell lines. Functional significance of NKX2-1 (NK2 homeobox 1) was evaluated by cell growth, apoptosis, and xenograft using clustered regularly interspaced short palindromic repeats-Cas9 (CRISPR-associated protein 9)-mediated deletion. NKX2-1-specific cistromic profiles were determined using chromatin immunoprecipitation followed by sequencing, and its functional transcriptional partners were determined using coimmunoprecipitation followed by mass spectrometry. Rb1flox/flox; Trp53flox/flox and Rb1flox/flox; Trp53flox/flox; Nkx2-1flox/flox mouse models were engineered to explore the function of Nkx2-1 in SCLC tumorigenesis. Epigenomic landscapes of six human SCLC specimens and 20 tumors from two mouse models were characterized. Measurements and Main Results: We identified two epigenomic subclusters of the major SCLC-A subtype: SCLC-Aα and SCLC-Aσ. SCLC-Aα was characterized by the presence of a super-enhancer at the NKX2-1 locus, which was observed in human SCLC specimens and a murine SCLC model. We found that NKX2-1, a dual lung and neural lineage factor, is uniquely relevant in SCLC-Aα. In addition, we found that maintenance of this neural identity in SCLC-Aα is mediated by collaborative transcriptional activity with another neuronal transcriptional factor, SOX1 (SRY-box transcription factor 1). Conclusions: We comprehensively describe additional epigenomic heterogeneity of the major SCLC-A subtype and define the SCLC-Aα subtype by the core regulatory circuitry of NKX2-1 and SOX1 super-enhancers and their functional collaborations to maintain neuronal linage state.

Coexistence of carcinoid tumor and adenocarcinoma of the lung; morphological, immunohistochemical and genetic analyses, a case report

Background

Pulmonary carcinoid tumors rarely coexist with non-small cell lung carcinoma, and only nine cases have been reported previously. The pathogenesis and origin of these combined tumors remain unclear because of its rarity.

Case presentation

We examined two cases of adenocarcinoma coexisting with a typical or atypical carcinoid tumor: Case 1 was a 77-year-old woman and Case 2 was an 83-year-old woman. Both of these cases had no respiratory symptoms, and underwent pulmonary lobectomies due to incidentally detected lung nodules. Recurrence and metastases were not detected after the surgery. Histologically, carcinoid and adenocarcinoma components were present in both cases. The two components coexisted without mixing with each other. Next-generation sequencing was performed on the two components in these cases. In each case, no common genetic variants were detected.

Conclusion

We considered that our cases could histologically and genetically represent collision tumors that did not share common progenitor cells. Comprehensive analyses such as whole genome sequencing could provide important information for elucidating the pathogenesis of adenocarcinoma and carcinoid components.

A Novel Strategy for the Diagnosis of Pulmonary High-Grade Neuroendocrine Tumor

Correctly diagnosing a histologic type of lung cancer is important for selecting the appropriate treatment because the aggressiveness, chemotherapy regimen, surgical approach, and prognosis vary significantly among histologic types. Pulmonary NETs, which are characterized by neuroendocrine morphologies, represent approximately 20% of all lung cancers. In particular, high-grade neuroendocrine tumors (small cell lung cancer and large cell neuroendocrine tumor) are highly proliferative cancers that have a poorer prognosis than other non-small cell lung cancers. The combination of hematoxylin and eosin staining, Ki-67, and immunostaining of classic neuroendocrine markers, such as chromogranin A, CD56, and synaptophysin, are normally used to diagnose high-grade neuroendocrine tumors; however, they are frequently heterogeneous. This article reviews the diagnostic methods of lung cancer diagnosis focused on immunostaining. In particular, we describe the usefulness of immunostaining by Stathmin-1, which is a cytosolic phosphoprotein and a key regulator of cell division due to its microtubule depolymerization in a phosphorylation-dependent manner, for the diagnosis of high-grade neuroendocrine tumors.

An analysis of 130 neuroendocrine tumors G3 regarding prevalence, origin, metastasis, and diagnostic features

Limited data exist on high-grade neuroendocrine tumors (NETs G3) which represent a new category among neuroendocrine neoplasms (NEN). We analyzed NETs G3 in a consultation series regarding prevalence, origin, metastasis, and diagnostic problems. Based on the WHO classification of digestive system tumors, 130 NETs G3 (9%) were identified in 1513 NENs. NET G3 samples were more often obtained from metastatic sites (69%) than NET G1/G2 samples (24%). NET G3 metastases presented most frequently in the liver (74%) and originated from the pancreas (38/90, 42%), followed by the lung (9%), ileum (7%), stomach (3%), rectum (1%), and rare sites (2%) such as the prostate and breast. The primaries remained unknown in 15%. NETs G3 had a median Ki67 of 30% that distinguished them from NECs (60%), though with great overlap. The expression of site-specific markers, p53, Rb1, and SST2 was similar in NETs G3 and NETs G1/G2, except for p53 and Rb1 which were abnormally expressed in 8% and 7% of liver metastases from NET G3 but not from NET G1/G2. NETs G3 were frequently referred as NECs (39%) but could be well distinguished from NECs by normal p53 (92% versus 21%) and Rb1 expression (93% versus 41%) expression. In conclusion, NETs G3 are frequently discovered as liver metastases from pancreatic or pulmonary primaries and are often misinterpreted as NEC. p53 and Rb1 are powerful markers in the distinction of NET G3 from NEC. Rarely, carcinomas from non-digestive, non-pulmonary organs with neuroendocrine features may present as NET G3.

An algorithmic approach utilizing CK7, TTF1, beta-catenin, CDX2, and SSTR2A can help differentiate between gastrointestinal and pulmonary neuroendocrine carcinomas

Primary gastrointestinal neuroendocrine carcinoma (GI-NEC) cannot be distinguished morphologically from pulmonary neuroendocrine carcinoma (P-NEC). This can present a significant diagnostic challenge in cases where site of origin cannot be readily determined. To identify immunohistochemical (IHC) markers that can be used to reliably distinguish between GI-NECs and P-NECs, we constructed 3-mm tissue microarrays, one containing 13 GI-NECs and one containing 20 P-NECs. IHC was performed on both microarrays using 21 stains: AE1/AE3, CK7, CK20, synaptophysin, chromogranin, CD56, INSM1, SSTR2A, CDX2, SATB2, TTF1, Napsin A, PR, GATA3, PAX8, ISL1, beta-catenin, AFP, SMAD4, Rb, and p53. For GI-NEC, the most strongly expressed marker was synaptophysin (mean H-score 248), while AE1/AE3 was the most strongly expressed in P-NEC (mean H-score 230), which was stronger than in GI-NEC (p = 0.011). Other markers that were stronger overall in P-NEC than in GI-NEC included CK7 (p < 0.0001) and TTF1 (p < 0.0001). Markers that were stronger overall in GI-NEC than in P-NEC included SSTR2A (p = 0.0021), SATB2 (p = 0.018), CDX2 (p = 0.019), and beta-catenin (nuclear; p = 0.029). SMAD4, Rb, and p53 showed similar rates of abnormal protein expression. Based on these results, a stepwise algorithmic approach utilizing CK7, TTF1, beta-catenin, CDX2, and SSTR2A had a 91% overall accuracy in distinguishing these GI-NEC from P-NEC. This was tested on a second cohort of 10 metastatic GI-NEC and 10 metastatic P-NEC, with an accuracy in this cohort of 85% and an overall accuracy of 89% for the 53 cases tested. Our algorithm reasonably discriminates GI-NEC from P-NEC using currently available IHC stains.

Recent advances and conceptual changes in the classification of neuroendocrine tumors of the thymus

Neuroendocrine tumors of the thymus (TNET) are exceedingly rare neoplasms. Their histomorphology is identical to neuroendocrine tumors elsewhere in the body (in particular the lungs) and bears no similarity with thymomas and thymic carcinomas. Recent molecular findings have profoundly changed our perception of these tumors and may impact future histological classification systems.

Integrated Immunohistochemical Study on Small-Cell Carcinoma of the Lung Focusing on Transcription and Co-Transcription Factors

Small-cell lung cancer (SCLC) is an aggressive malignant cancer that is classified into four subtypes based on the expression of the following key transcription and co-transcription factors: ASCL1, NEUROD1, YAP1, and POU2F3. The protein expression levels of these key molecules may be important for the formation of SCLC characteristics in a molecular subtype-specific manner. We expect that immunohistochemistry (IHC) of these molecules may facilitate the diagnosis of the specific SCLC molecular subtype and aid in the appropriate selection of individualized treatments. We attempted IHC of the four key factors and 26 candidate SCLC target molecules selected from the gene expression omnibus datasets of 47 SCLC samples, which were grouped based on positive or negative results for the four key molecules. We examined differences in the expression levels of the candidate targets and key molecules. ASCL1 showed the highest positive rate in SCLC samples, and significant differences were observed in the expression levels of some target molecules between the ASCL1-positive and ASCL1-negative groups. Furthermore, the four key molecules were coordinately and simultaneously expressed in SCLC cells. An IHC study of ASCL1-positive samples showed many candidate SCLC target molecules, and IHC could become an essential method for determining SCLC molecular subtypes.

TTF1 Expression in Pulmonary Metastatic Rectal Adenocarcinoma

Thyroid transcription factor (TTF-1) is a tissue-specific nuclear transcription factor expressed developing thyroid, respiratory epithelium, and diencephalon. TTF-1 is thought to be expressed specifically in most thyroid tumors and in a significant subset of pulmonary neoplasms. However, recent studies on its expression in extrapulmonary carcinomas have demonstrated that TTF-1 is not as specific for lung and thyroid carcinomas as was previously thought: positivity of this marker can be observed, although much less frequently, in some carcinomas arising in other organs, such as the ovaries, endometrium, colon, and breast, as well as in some tumors of the central nervous system. Case reports of patients with TTF-1-positive colon adenocarcinoma are present in medical literature, but there are only a few cases of TTF-1-positive rectal adenocarcinoma. We present the case of a patient with rectal adenocarcinoma with lung metastasis found to be TTF-1-positive on immunohistochemistry. A review of the available literature is also included.

Immunohistochemical Biomarkers of Gastrointestinal, Pancreatic, Pulmonary, and Thymic Neuroendocrine Neoplasms

Neuroendocrine neoplasms (NENs) are a heterogeneous group of epithelial neoplastic proliferations that irrespective of their primary site share features of neural and endocrine differentiation including the presence of secretory granules, synaptic-like vesicles, and the ability to produce amine and/or peptide hormones. NENs encompass a wide spectrum of neoplasms ranging from well-differentiated indolent tumors to highly aggressive poorly differentiated neuroendocrine carcinomas. Most cases arise in the digestive system and in thoracic organs, i.e., the lung and thymus. A correct diagnostic approach is crucial for the management of patients with both digestive and thoracic NENs, because their high clinical and biological heterogeneity is related to their prognosis and response to therapy. In this context, immunohistochemistry represents an indispensable diagnostic tool that pathologists need to use for the correct diagnosis and classification of such neoplasms. In addition, immunohistochemistry is also useful in identifying prognostic and theranostic markers. In the present article, the authors will review the role of immunohistochemistry in the routine workup of digestive and thoracic NENs.

Pathology of Neuroendocrine Tumours of the Female Genital Tract

Neuroendocrine tumours are uncommon or rare at all sites in the female genital tract. The 2014 World Health Organisation (WHO) Classification of neuroendocrine tumours of the endometrium, cervix, vagina and vulva has been updated with adoption of the terms low-grade neuroendocrine tumour and high-grade neuroendocrine carcinoma. In the endometrium and cervix, high-grade neoplasms are much more prevalent than low-grade and are more common in the cervix than the corpus. In the ovary, low-grade tumours are more common than high-grade carcinomas and the term carcinoid tumour is still used in WHO 2014. The term ovarian small-cell carcinoma of pulmonary type is included in WHO 2014 for a tumour which in other organs is termed high small-cell neuroendocrine carcinoma. Neuroendocrine tumours at various sites within the female genital tract often occur in association with other neoplasms and more uncommonly in pure form.

Small cell lung cancer tumors and preclinical models display heterogeneity of neuroendocrine phenotypes

Background

Small cell lung cancer (SCLC) is a deadly, high grade neuroendocrine (NE) tumor without recognized morphologic heterogeneity. However, over 30 years ago we described a SCLC subtype with "variant" morphology which did not express some NE markers and exhibited more aggressive growth.

Methods

To quantitate NE properties of SCLCs, we developed a 50-gene expression-based NE score that could be applied to human SCLC tumors and cell lines, and genetically engineered mouse (GEM) models. We identified high and low NE subtypes of SCLC in all of our sample types, and characterized their properties.

Results

We found that 16% of human SCLC tumors and 10% of SCLC cell lines were of the low NE subtype, as well as cell lines from the GEM model. High NE SCLC lines grew as non-adherent floating aggregates or spheroids while Low NE lines had morphologic features of the variant subtype and grew as loosely attached cells. While the high NE subtype expressed one of the NE lineage master transcription factors ASCL1 or NEUROD1, together with NKX2-1, the entire range of NE markers, and lacked expression of the neuronal and NE repressor REST, the low NE subtype had lost expression of most NE markers, ASCL1, NEUROD1 and NKX2-1 and expressed REST. The low NE subtype had undergone epithelial mesenchymal transition (EMT) and had activated the Notch, Hippo and TGFβ pathways and MYC oncogene . Importantly, the high and low NE group of SCLC lines had similar gene expression profiles as their SCLC tumor counterparts.

Conclusions

SCLC tumors and cell lines can exhibit distinct inter-tumor heterogeneity with respect to expression of NE features. Loss of NE expression results in major alterations in morphology, growth characteristics, and molecular properties. These findings have major clinical implications as the two subtypes are predicted to have very different responses to targeted therapies.

Orthopedia homeobox is preferentially expressed in typical carcinoids of the lung

BACKGROUND

Twenty-seven percent of neuroendocrine tumors (NETs) are associated with distant metastases, and in some patients, the primary site is unknown. Orthopedia homeobox protein (OTP) has been described as a useful marker for lung carcinoids (LCs) and for separating low-grade typical carcinoids (TCs) from intermediate-grade atypical carcinoids (ACs) in resection specimens. This study evaluated OTP, thyroid transcription factor 1 (TTF-1), and Ki-67 expression in fine-needle aspiration (FNA) samples of various NETs.

METHODS

A search for NETs diagnosed via FNA with subsequent resection was performed. Cell block sections were stained for OTP, TTF-1, and mindbomb E3 ubiquitin protein ligase 1 (Mib-1). Nuclear expression for OTP and TTF-1 was considered positive. Nuclear Ki-67 staining was reported as a percentage. Results were correlated with the grade and primary site for resection specimens.

RESULTS

Sixty-three FNA samples of NETs were identified: 14 liver samples, 14 pancreatic samples, 13 lymph node samples, 12 lung samples, 3 retroperitoneum samples, 2 small intestine samples, and 5 other samples. OTP was positive in 12 of 63 NETs (19%) from the following sites: lung (n = 8), liver (lung primary; n = 2), skin (n = 1), and lymph node (lung primary; n = 1). In well-differentiated NETs, only LCs were OTP-positive, whereas TTF-1 was positive in LCs and nonlung NETs (67% vs 7%). Within the LC category, OTP was positive in 100% of the TCs versus 17% of the ACs.

CONCLUSIONS

OTP is specific for LCs because well-differentiated nonlung NETs are negative for OTP. OTP preferentially stains TCs over ACs. In well-differentiated NETs, OTP staining is highly specific for LCs, and in combination with a low Ki-67 index, it suggests a pulmonary TC. Cancer Cytopathol 2018;126:236-42. © 2018 American Cancer Society.

Small-cell lung cancer: what we know, what we need to know and the path forward

Small-cell lung cancer (SCLC) is a deadly tumour accounting for approximately 15% of lung cancers and is pathologically, molecularly, biologically and clinically very different from other lung cancers. While the majority of tumours express a neuroendocrine programme (integrating neural and endocrine properties), an important subset of tumours have low or absent expression of this programme. The probable initiating molecular events are inactivation of TP53 and RB1, as well as frequent disruption of several signalling networks, including Notch signalling. SCLC, when diagnosed, is usually widely metastatic and initially responds to cytotoxic therapy but nearly always rapidly relapses with resistance to further therapies. There were no important therapeutic clinical advances for 30 years, leading SCLC to be designated a 'recalcitrant cancer'. Scientific studies are hampered by a lack of tissue availability. However, over the past 5 years, there has been a worldwide resurgence of studies on SCLC, including comprehensive molecular analyses, the development of relevant genetically engineered mouse models and the establishment of patient-derived xenografts. These studies have led to the discovery of new potential therapeutic vulnerabilities for SCLC and therefore to new clinical trials. Thus, while the past has been bleak, the future offers greater promise.

Immunohistochemistry, carcinomas of unknown primary, and incidence rates

Pathologists use immunohistochemistry is their day-to-day practices to assist in distinguishing site of origin of metastatic carcinomas. Here, the work-up is discussed neuroendocrine carcinomas, squamous cell carcinomas and adenocarcinomas with particular attention to tumor incident rates and predictive values of the best-performing immunohistochemical markers.

P16 is a useful supplemental diagnostic marker of pulmonary small cell carcinoma in small biopsies and cytology specimens

Pulmonary small cell carcinoma (SCLC) is usually diagnosed in small biopsy or cytological specimens based on cytomorphology; however in ambiguous cases diagnosis requires additional support by immunohistochemistry. While TP53 and RB1 alterations with secondary overexpression of p16 are mainstay events in SCLC pathogenesis, diagnostic value of p16-positivity in the diagnosis of SCLC has not yet been fully investigated. We examined the expression of p16, CD56, synaptophysin (SYP), chromogranin A and thyroid transcription factor-1 (TTF1) in a series of pulmonary and extrapulmonary small cell carcinomas, pulmonary carcinoids and non-small cell lung carcinomas, and compared diagnostic performance of these markers in the diagnosis of SCLC. P16 was positive in 95 of 101 SCLCs, and displayed highest diagnostic sensitivity of ~94%. Composite biomarkers CD56+p16+TTF1 and CD56+p16+SYP were both able to detect correctly all SCLC cases. Importantly, three (~3%) SCLC cases completely negative for all conventional markers displayed diffuse positivity for p16. CD56 and p16 demonstrated highest concordance between paired small biopsy and cytology specimens. 50% of squamous cell carcinomas, ~41% of adenocarcinoma/NSCLC-favour adenocarcinoma cases, and ~93% of extrapulmonary small cell carcinomas also showed p16-positivity. Combination of CD56, p16 and TTF1 produced diagnostic classifier that outperformed best single marker CD56 in differential diagnosis between SCLC and NSCLC. In conclusion, in the appropriate morphological context p16 represents a useful supplementary marker for diagnosis of SCLC, even in cases where only cytological material is available.

Recent updates on grading and classification of neuroendocrine tumors

Neuroendocrine tumors (NETs) are originating from neuroendocrine cells in diffuse endocrine systems. NETs are diagnosed by characteristic histologic features and immunoprofiles. Recent 2010 WHO classification for gastroenteropancreatic NETs introduced grading system based on mitotic count and Ki-67 proliferation index. Gastroenteropancreatic NETs are classified as NET grade 1, NET grade 2, and neuroendocrine carcinoma (NET grade 3). However, the carcinoid is still used in classification of NETs of the lung and uterine cervix. Some issues with grading system such as methodologies for evaluation of Ki-67 index and subclassification of neuroendocrine carcinoma (NET grade 3) are arising. The importance of Ki-67 labeling index is emerging in differential diagnosis of lung carcinoids. In this review, we focus on recent grading and classification of NETs and related issues in various organs, including gastrointestinal tract, pancreas, lung, and female reproductive organs.

Posttranslational modification of β-catenin is associated with pathogenic fibroblastic changes in bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is a common complication of premature birth. The histopathology of BPD is characterized by an arrest of alveolarization with fibroblast activation. The Wnt/β-catenin signaling pathway is important in early lung development. When Wnt signaling is active, phosphorylation of β-catenin by tyrosine kinases at activating sites, specifically at tyrosine 489 (Y489), correlates with nuclear localization of β-catenin. We examined fetal lung tissue, lung tissue from term newborns, and lung tissue from infants who died with BPD; we found nuclear β-catenin phosphorylation at Y489 in epithelial and mesenchymal cells in fetal tissue and BPD tissue, but not in the lungs of term infants. Using a 3D human organoid model, we found increased nuclear localization of β-catenin phosphorylated at Y489 (p-β-catenin^Y489) after exposure to alternating hypoxia and hyperoxia compared with organoids cultured in normoxia. Exogenous stimulation of the canonical Wnt pathway in organoids was sufficient to cause nuclear localization of p-β-catenin^Y489 in normoxia and mimicked the pattern of α-smooth muscle actin (α-SMA) expression seen with fibroblastic activation from oxidative stress. Treatment of organoids with a tyrosine kinase inhibitor prior to cyclic hypoxia-hyperoxia inhibited nuclear localization of p-β-catenin^Y489 and prevented α-SMA expression by fibroblasts. Posttranslational phosphorylation of β-catenin is a transient feature of normal lung development. Moreover, the persistence of p-β-catenin^Y489 is a durable marker of fibroblast activation in BPD and may play an important role in BPD disease pathobiology.

Mixed Neuroendocrine-Nonneuroendocrine Neoplasms (MiNENs): Unifying the Concept of a Heterogeneous Group of Neoplasms

The wide application of immunohistochemistry to the study of tumors has led to the recognition that epithelial neoplasms composed of both a neuroendocrine and nonneuroendocrine component are not as rare as traditionally believed. It has been recommended that mixed neuroendocrine-nonneuroendocrine epithelial neoplasms are classified as only those in which either component represents at least 30 % of the lesion but this cutoff has not been universally accepted. Moreover, since their pathogenetic and clinical features are still unclear, mixed neuroendocrine-nonneuroendocrine epithelial neoplasms are not included as a separate clinicopathological entity in most WHO classifications, although they have been observed in virtually all organs. In the WHO classification of digestive tumors, mixed neuroendocrine-nonneuroendocrine neoplasm is considered a specific type and is defined as mixed adenoneuroendocrine carcinoma, a definition that has not been accepted for other organs. In fact, this term does not adequately convey the morphological and biological heterogeneity of digestive mixed neoplasms and has created some misunderstanding among both pathologists and clinicians. In the present study, we have reviewed the literature on mixed neuroendocrine-nonneuroendocrine epithelial neoplasms reported in the pituitary, thyroid, nasal cavity, larynx, lung, digestive system, urinary system, male and female genital organs, and skin to give the reader an overview of the most important clinicopathological features and morphological criteria for diagnosing each entity. We also propose to use the term "mixed neuroendocrine-nonneuroendocrine neoplasm (MiNEN)" to define and to unify the concept of this heterogeneous group of neoplasms, which show different characteristics mainly depending on the type of neuroendocrine and nonneuroendocrine components.

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.

mASH1 is Highly Specific for Neuroendocrine Carcinomas: An Immunohistochemical Evaluation on Normal and Various Neoplastic Tissues

CONTEXT

-High-grade neuroendocrine carcinomas and carcinoids can arise in different sites such as lung, gastrointestinal tract, prostate, and skin. Classic neuroendocrine markers such as CD56, synaptophysin, and chromogranin cannot distinguish carcinoids from high-grade neuroendocrine carcinomas. Recently, mouse monoclonal mASH1 has been shown to help discriminate carcinoids from high-grade neuroendocrine carcinomas in various neoplastic sites. To date, there have been no comprehensive immunohistochemistry studies with mASH1 on nonneuroendocrine neoplasms.

OBJECTIVE

-To evaluate the specificity and sensitivity of mASH1 in various normal and neoplastic tissues, including lung cancers.

DESIGN

-Formalin-fixed, paraffin-embedded tissue microarrays consisting of normal tissues and various neoplastic tissues were immunohistochemically evaluated with mASH1.

RESULTS

-In normal tissues (n = 30), mASH1 (nuclear staining) was sparsely expressed in the molecular cell layer, white matter, and granular cell layer of cerebellum; C cells in thyroid; and epithelial cells in thymus. In lung cancers, mASH1 stained 1.1% (1 of 93) of adenocarcinomas, 0.9% (1 of 111) of squamous cell carcinomas, 0% (0 of 30) of large cell carcinomas, 66.7% (6 of 9) of large cell neuroendocrine carcinomas, and 82.5% (94 of 114) of small cell carcinomas. In various other neoplastic tissues (n = 1114), mASH1 was expressed in thyroid medullary carcinomas, thymic carcinomas, and brain cancers; mASH1 was also expressed in a very low percentage of breast carcinomas, ovarian cancers, and pancreatic neuroendocrine tumors. All typical carcinoids of various sites were negative (0 of 11), however, in lung atypical carcinoids, mASH1 was expressed in 42.9% (9 of 21).

CONCLUSIONS

-Although not organ specific, mASH1 is highly specific for high-grade neuroendocrine carcinomas versus carcinoids and other nonneuroendocrine neoplasms.

Diagnostic value of thyroid transcription factor-1 for pleural or other serous metastases of pulmonary adenocarcinoma: a meta-analysis

The role of thyroid transcription factor 1 (TTF-1) in the diagnosis of metastatic pulmonary adenocarcinomas in pleural, pericardial, and peritoneal effusions has not been defined. This study aimed to assess the overall diagnostic accuracy of TTF-1 for metastatic pulmonary adenocarcinomas in pleural or other effusions. Literature search was conducted in PubMed, EMBASE, and other databases to find eligible publications. Quality was assessed according to standardized QUADAS-2 criteria. Sensitivity, specificity, positive/negative likelihood ratio (PLR/NLR), and diagnostic odds ratio (DOR) were pooled. Summary receiver operating characteristic (SROC) curves were used to assess overall performance of the TTF-1 assay. A systematic search revealed 20 studies comprising a total of 1,213 subjects in this meta-analysis. The summary estimates were listed as follows: sensitivity, 0.74 (95% CI: 0.69–0.79); specificity, 0.99 (95% CI: 0.97–1.00); PLR, 78.16 (95% CI: 27.15–225.05); NLR, 0.26 (95% CI: 0.22–0.32); and diagnostic odds ratio, 297.75 (95% CI: 104.16–851.19). Estimated positive and negative post-probability values for metastatic pulmonary adenocarcinomas prevalence of 20% were 95% and 6%, respectively. The area under the SROC curve was 0.96. TTF-1 shows significant potential as a diagnostic marker to differentiate metastatic pulmonary from non-pulmonary adenocarcinomas in pleural or other effusions. These results justify larger, more rigorous studies to confirm such a diagnostic role.

Problems with the diagnosis of metastatic neuroendocrine neoplasms. Which diagnostic criteria should we use to determine tumor origin and help guide therapy?

Neuroendocrine neoplasms (NENs) can often present with metastatic disease before the primary tumor is discovered. Metastatic lesions are generally classified as well differentiated and poorly differentiated for prognostic and therapeutic purposes. In addition, for well-differentiated neuroendocrine tumors (WDNETs), pathologists are expected to determine the site of origin, if not already known, and grade the tumors. However, it is often difficult for pathologists to provide this information with certainty without knowing the site of tumor origin, as different criteria have been proposed by WHO for classification of gastrointestinal and pulmonary NENs. In this review, we will discuss the current classification and grading schema of NENs and their impact on clinical care, the differential diagnosis of NENs, the use of immunohistochemical stains that help identify tumor site of origin, and a proposed approach for the diagnosis and classification of metastatic NENs.

Breast metastasis as the first clinical manifestation of ileal neuroendocrine tumor. A challenging diagnosis with relevant clinical implications

Ileal neuroendocrine tumors are slow-growing grade 1 or, more rarely, grade 2 neuroendocrine tumors which, however, are frequently metastatic to regional lymph nodes and the liver. A few cases of ileal neuroendocrine tumors that are metastatic to the breast have also been reported in the medical literature. The knowledge of this uncommon clinical presentation is of great importance because it needs to be differentiated from primary breast carcinomas with neuroendocrine features, which represent completely different entities with a different therapeutic approach. The diagnosis of a breast metastasis from an ileal neuroendocrine tumor and its distinction from a well-differentiated primary neuroendocrine tumor of the breast is a challenging task for clinicians and pathologists. This workup is particularly difficult when the breast lesion is the first sign of malignancy. In the present paper, we describe the clinicopathological features of an ileal neuroendocrine tumor first presenting with a breast metastasis in a 50-year-old woman and we discuss the key diagnostic features for the differential diagnosis with primary well-differentiated neuroendocrine tumor of the breast. Moreover, we have reviewed the medical literature to give the reader a comprehensive overview on this topic.

Co-expression of TTF-1 and neuroendocrine markers in the human fetal lung and pulmonary neuroendocrine tumors

The expression pattern of thyroid transcription factor 1 (TTF-1) and neuroendocrine markers, neuron cell adhesion molecule (NCAM; CD56), chromogranin A (CgA) and synaptophysin (Syp), of different lung cell lineages was histologically analyzed in 15 normal human fetal lungs and 12 neuroendocrine tumors (NETs) using immunohistochemical methods. During pseudoglandular phase strong nuclear TTF-1 staining was detected in the columnar nonciliated epithelial cells, while NCAM, CgA and Syp had a moderate expression in the proximal airways and mild expression in the distal airways. Neuroendocrine cells (NECs) in proximal lung airway were co-localizing TTF-1 and other neuroendocrine markers while neuroendocrine bodies (NEBs) exhibit only staining with NCAM and Syp. In the canalicular phase TTF-1 nuclear staining was expressed only in several epithelial cells in proximal airways, while budding airways epithelium showed strong TTF-1 expression. Expression of NCAM, CgA and Syp in this phase equals the one in pseudoglandular phase. NEBs cells were co-localizing TTF-1 and NCAM in proximal airways and few NECs in distal airway were co-localizing TTF-1 and Syp. TTF-1 staining in the saccular phase was limited to subsets of epithelial cells in the proximal airways with stronger positivity in the distal airways. NCAM expression is moderate only in proximal airways, while Syp and CgA show mild expression in proximal and distal airways. NECs were co-localizing TTF-1 and NCAM in proximal lung airway. With regard to NECs, all small cell lung cancer (SCLC) cells had strong TTF-1, NCAM, Syp and CgA positivity and TTF-1 co-localized with other neuroendocrine markers. All pulmonary typical carcinoids were TTF-1 negative, while pulmonary atypical carcinoids were focal positive for TTF-1 and some neoplastic cells co-localized TTF-1 with neuroendocrine markers. Our results indicate that TTF-1 expression in NECs suggests a possible role in their normal development and differentiation. Our results also indicate that possible cell of origin for poorly differentiated SCLC and some atypical carcinoid could be a progenitor cell in neuroendocrine lineage while in typical carcinoids possible cell of origin is localized in terminally differentiated NECs.

Therapeutic biomarkers in lung neuroendocrine neoplasia

The well-known classification of neuroendocrine neoplasms of the lung into four major subtypes (including typical and atypical carcinoids and small- and large-cell neuroendocrine carcinomas) has a proven prognostic validity but only partially helps to predict the response to specific therapies. Therapeutic biomarkers are incompletely known and include morphological, immunophenotypic, and molecular markers. Morphology alone has no specific predictive role, nor has any immunophenotypic marker been proven to bear predictive implications. Ki67 is a relevant prognostic marker and can indirectly predict response to chemotherapy, when levels are extremely high in high-grade neuroendocrine (NE) carcinomas. The expression of somatostatin receptors, especially of the type 2A, has been shown to predict response to somatostatin analog treatments, paralleling the information derived from octreotide scintigraphy. mTOR pathway is targeted by specific inhibitors, but the exact cellular molecules predicting response are still to be defined. It seems that high levels of phosphorylated forms of mTOR and of its downstream factor S6K are associated to a better response to rapalogs in experimental models. Data from gene expression profiling and mutational analyses are currently emerging, providing a more detailed map of different molecular activation pathways, potentially leading to a more accurate molecular classification of lung NE tumors as well as to the discovery of new therapeutic targets. The combination of mutational profiles with those of upregulated or downregulated genes also by gene gains or losses may ultimately provide a better characterization of NE tumor histological types in terms of response to specific chemotherapy or biotherapy.

High-grade poorly differentiated neuroendocrine carcinomas of the gastroenteropancreatic system: from morphology to proliferation and back

Poorly differentiated neuroendocrine carcinomas (PDNECs) of the gastroenteropancreatic system (GEP) are a heterogeneous group of aggressive malignancies with a high propensity for distant metastases and an ominous prognosis. They have traditionally been divided into small and large cell subtypes on morphological grounds. However, histological diagnosis needs to be supported by immunohistochemistry to avoid possible misdiagnoses either with the more frequent poorly differentiated adenocarcinomas and squamous cell carcinomas or with lymphomas and mesenchymal neoplasms. Although it is well known that GEP PDNECs are associated with a poor prognosis, data from some published studies seem to suggest that there is a fraction of patients with PDNECs who have better survival than expected. GEP PDNECs are currently classified according to the criteria proposed in the 2010 WHO classification. They are simply called neuroendocrine carcinomas (NECs) and are defined by mitotic count >20 × 10 HPF and/or Ki-67 labeling index >20 %. However, a few recent papers have indicated that some NECs, as defined by the 2010 WHO scheme, do not show a poorly differentiated morphology as expected. This category seems to show a better prognosis and, especially, does not respond to cisplatin-based chemotherapy, which represents the goal standard therapeutic approach to high-grade PDNECs. In the present review, the main morphological, immunohistochemical, and prognostic features will be discussed as well as the opportunity to introduce a new category characterized by well to moderately differentiated morphology associated with high proliferation (mitotic count >20 × 10 HPF and/or Ki-67 index >20 %).

Primary gastric Merkel cell carcinoma harboring DNA polyomavirus: first description of an unusual high-grade neuroendocrine carcinoma

Merkel cell carcinoma (MCC) is a skin cancer that can also rarely arise in extracutaneous sites including mucosal surfaces. About 80% of MCCs harbor the Merkel cell polyomavirus (MCPyV). All cases of gastric MCCs so far reported were metastases from cutaneous sources. In the present article, we describe for the first time a primary gastric MCC harboring MCPyV. A 72-year-old man presented to clinical observation due to epigastric pain. Upper endoscopy revealed an ulcerated gastric tumor. The patient underwent total gastrectomy. The tumor was composed of mitotically active monomorphic small cells showing round nuclei with finely dispersed chromatin arranged in sheets and nests with large areas of necrosis. Tumor cells were positive for neuroendocrine markers and showed paranuclear dot immunoreactivity for cytokeratin 20. MCPyV was demonstrated with immunohistochemistry and electron microscopy, which showed intranuclear and intracytoplasmic viral particles. The MCPyV DNA in tumor cells was demonstrated with polymerase chain reaction analysis.

Neuroendocrine tumours--challenges in the diagnosis and classification of pulmonary neuroendocrine tumours

Pulmonary neuroendocrine (NE) proliferations are a diverse group of disorders which share distinct cytological, architectural and biosynthetic features. Tumours composed of NE cells are dispersed among different tumour categories in the WHO classification of tumours and as such do not conform to a singular group with regards to treatment and prognosis. This is reflected by the highly variable behaviour of NE proliferations, ranging from asymptomatic, for instance in diffuse idiopathic pulmonary NE cell hyperplasia and tumourlets, to highly malignant cancers such as small cell lung cancer and large cell NE carcinoma. In this review NE proliferations are described as distinct entities ranging from low grade lesions to high grade cancers. The differential diagnoses are considered with each of the entries. Finally, mention is made of tumours which may show some NE features.

[Pathological characteristic and clinical management of pulmonary carcinoid]

背景与目的

肺类癌采取以手术为主的多学科治疗，准确及时的病理诊断至关重要。本研究探讨肺类癌的病理特质，结合回顾性分析患者的转归预后，为临床决策提供依据。

方法

收集支气管肺内发生的类癌手术标本32例，回顾性分析患者相关的临床病理资料，系统研究病灶病理学表现与临床诊断和治疗效果的相关性。

结果

32例肺类癌患者中，典型类癌18例，不典型类癌14例；男女性别比为2.2:1；平均年龄（44±15）岁；近半数患者无症状；肿瘤最大径（3.1±1.3）cm；绝大多数为Ⅰ期患者（84.4%, 27/32），余Ⅱa期2例，Ⅲa期2例，Ⅳ期1例；随访时间为5.2年-9.7年；其中典型类癌随访15例，5年无进展生存率为100%；不典型类癌随访12例，5年无进展生存率为92.9%；肺类癌病理组织学的特质是典型的神经内分泌形态伴细胞角蛋白阳性，嗜铬素A、突触素和CD56等神经内分泌指标的表达，Ki-67指数的高低有助于鉴别诊断。

结论

肺类癌的病理鉴别诊断应结合相关酶标染色，积极争取手术是适宜的临床决策。

Simultaneous multi-antibody staining in non-small cell lung cancer strengthens diagnostic accuracy especially in small tissue samples

Histological subclassification of non-small cell lung cancer (NSCLC) has growing therapeutic impact. In advanced cancer stages tissue specimens are usually bioptically collected. These small samples are of extraordinary value since molecular analyses are gaining importance for targeted therapies. We therefore studied the feasibility, diagnostic accuracy, economic and prognostic effects of a tissue sparing simultaneous multi-antibody assay for subclassification of NSCLC. Of 265 NSCLC patients tissue multi arrays (TMA) were constructed to simulate biopsy samples. TMAs were stained by a simultaneous bi-color multi-antibody assay consisting of TTF1, Vimentin, p63 and neuroendocrine markers (CD56, chromogranin A, synaptophysin). Classification was based mainly on the current proposal of the IASLC with a hierarchical decision tree for subclassification into adenocarcinoma (LAC), squamous cell carcinoma (SCC), large cell neuroendocrine carcinoma (LCNEC) and NSCLC not otherwise specified. Investigation of tumor heterogeneity showed an explicit lower variation for immunohistochemical analyses compared to conventional classification. Furthermore, survival analysis of our combined immunohistochemical classification revealed distinct separation of each entity's survival curve. This was statistically significant for therapeutically important subgroups (p = 0.045). As morphological and molecular cancer testing is emerging, our multi-antibody assay in combination with standardized classification delivers accurate and reliable separation of histomorphological diagnoses. Additionally, it permits clinically relevant subtyping of NSCLC including LCNEC. Our multi-antibody assay may therefore be of special value, especially in diagnosing small biopsies. It futher delivers substantial prognostic information with therapeutic consequences. Integration of immunohistochemical subtyping including investigation of neuroendocrine differentiation into standard histopathological classification of NSCLC must, therefore, be considered.

Achaete-scute homolog 1 as a marker of poorly differentiated neuroendocrine carcinomas of different sites: a validation study using immunohistochemistry and quantitative real-time polymerase chain reaction on 335 cases

Neuroendocrine carcinomas show overlapping morphological and immunohistochemical features independently of their site of origin, which makes identification of the primary location problematic when they are diagnosed as metastases of unknown origin. Neuroendocrine carcinomas are easily morphologically differentiated from neuroendocrine tumors in surgical material, although this distinction can be difficult when using small biopsy specimens. The diagnostic usefulness of different transcription factors as site-specific markers or as discriminating markers between neuroendocrine carcinomas and neuroendocrine tumors has been previously studied with sometimes contradictory results. In this respect, the role of achaete-scute homolog 1 has been poorly investigated, although some recent findings demonstrate its expression in neuroendocrine carcinomas. Using immunohistochemistry and quantitative real-time polymerase chain reaction, we investigated the expression of achaete-scute homolog 1 in 335 neuroendocrine neoplasms (194 neuroendocrine carcinomas and 141 neuroendocrine tumors) of different sites, to check its possible utility as diagnostic marker. High concordance between immunohistochemical and molecular findings was found. Achaete-scute homolog 1 expression was identified in 82% of lung neuroendocrine carcinomas and 70% of extrapulmonary neuroendocrine carcinomas. Achaete-scute homolog 1 was not detected in any gastroenteropancreatic neuroendocrine tumor and was found in only a minority of lung carcinoids. The diagnostic sensitivity and specificity of achaete-scute homolog 1 expression were 82.4% and 89.7% in distinguishing neuroendocrine carcinomas from neuroendocrine tumors of the lung, 40.6% and 100% to differentiate extrapulmonary neuroendocrine carcinomas from neuroendocrine tumors, and 82.4% and 59.4% in distinguishing lung from extrapulmonary neuroendocrine carcinomas. Our data suggest that achaete-scute homolog 1 is not a site-specific marker. However, achaete-scute homolog 1 may be proposed as a diagnostic marker of poor differentiation and may help to differentiate neuroendocrine carcinomas from neuroendocrine tumors in difficult cases.

Transcriptional programs controlling perinatal lung maturation

The timing of lung maturation is controlled precisely by complex genetic and cellular programs. Lung immaturity following preterm birth frequently results in Respiratory Distress Syndrome (RDS) and Broncho-Pulmonary Dysplasia (BPD), which are leading causes of mortality and morbidity in preterm infants. Mechanisms synchronizing gestational length and lung maturation remain to be elucidated. In this study, we designed a genome-wide mRNA expression time-course study from E15.5 to Postnatal Day 0 (PN0) using lung RNAs from C57BL/6J (B6) and A/J mice that differ in gestational length by ∼30 hr (B6<A/J). Comprehensive bioinformatics and functional genomics analyses were used to identify key regulators, bioprocesses and transcriptional networks controlling lung maturation. We identified both temporal and strain dependent gene expression patterns during lung maturation. For time dependent changes, cell adhesion, vasculature development, and lipid metabolism/transport were major bioprocesses induced during the saccular stage of lung development at E16.5–E17.5. CEBPA, PPARG, VEGFA, CAV1 and CDH1 were found to be key signaling and transcriptional regulators of these processes. Innate defense/immune responses were induced at later gestational ages (E18.5–20.5), STAT1, AP1, and EGFR being important regulators of these responses. Expression of RNAs associated with the cell cycle and chromatin assembly was repressed during prenatal lung maturation and was regulated by FOXM1, PLK1, chromobox, and high mobility group families of transcription factors. Strain dependent lung mRNA expression differences peaked at E18.5. At this time, mRNAs regulating surfactant and innate immunity were more abundantly expressed in lungs of B6 (short gestation) than in A/J (long gestation) mice, while expression of genes involved in chromatin assembly and histone modification were expressed at lower levels in B6 than in A/J mice. The present study systemically mapped key regulators, bioprocesses, and transcriptional networks controlling lung maturation, providing the basis for new therapeutic strategies to enhance lung function in preterm infants.

Tissue-sparing application of the newly proposed IASLC/ATS/ERS classification of adenocarcinoma of the lung shows practical diagnostic and prognostic impact

The histologic subtype of non-small cell lung cancer (NSCLC) determines treatment strategies and the need for genetic analyses. Since most NSCLC are diagnosed on small biopsy or cytologic specimens, an accurate but tissue-sparing approach is necessary. To date, consensus for a general diagnostic algorithm is lacking. To test the diagnostic and clinical relevance of the recently published multidisciplinary guidelines by the International Association for the Study of Lung Cancer, American Thoracic Society, and European Respiratory Society, we examined 371 surgically resected NSCLCs brought into tissue microarray format. The antibody panel thyroid transcription factor-1 (TTF-1), p63, cytokeratin (CK)5/6, and CK7 is diagnostic for most cases (>94%). Faint/focal staining for CK7 is negligible for classificatory purposes. Grading adenocarcinomas according to histologic architecture is prognostically significant (median overall survival for well/moderate differentiation, 72.5 months; for poor differentiation, 38.5 months; P = .019). Double stains combining the aforementioned nuclear and membranous markers are highly diagnostic for NSCLC, conserving tumor tissue for subsequent analyses.

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.

Colorectal poorly differentiated neuroendocrine carcinomas and mixed adenoneuroendocrine carcinomas: insights into the diagnostic immunophenotype, assessment of methylation profile, and search for prognostic markers

Colorectal poorly differentiated neuroendocrine carcinomas (NECs) and mixed adenoneuroendocrine carcinomas (MANECs) are well-recognized entities generally known to be associated with biological aggressiveness and poor patient survival. However, a few published papers have highlighted the existence of a subgroup of tumors with a better survival than expected; however, to date, there are no established parameters that usefully identify this category. In the present study we have investigated the morphologic features, the CpG methylator phenotype (CIMP), microsatellite instability (MSI), and the immunohistochemical profile, including the expression of transcription factors (TTF1, ASH1, CDX2, and PAX5), stem cell markers (CD117 and CD34), and cytokeratins 7 and 20, in a series of 39 carcinomas (27 NECs and 12 MANECs) to better characterize such neoplasms and to search for prognostic indicators. No different patient survival was observed between NECs and MANECs. Neoplasms showed a heterogenous spectrum of morphologic and immunohistochemical features; however, only large-cell subtype, significant peritumoral lymphoid reaction, CD117 immunoreactivity, vascular invasion, and MSI/CIMP+ status were significantly correlated with prognosis on univariable analysis. Furthermore, vascular invasion and CD117 immunoreactivity were independent prognostic markers on multivariable analysis. In addition to these prognostic features, neoplasms showed different expression of transcription factors, stem cell markers, and cytokeratins that should be considered for diagnostic purposes and, especially, for discriminating among possible differential diagnoses.

Phenotyping of pulmonary carcinoids and a Ki-67-based grading approach

Pulmonary carcinoids (PC) are separated into typical (TC) and atypical carcinoids (ATC). However, the biological behavior cannot be reliably predicted, and in small biopsies differential diagnosis can be challenging. To provide a basis for a grading approach, we analyzed mitoses and the proliferative index (PI; Ki-67) of 200 PC specimens (TC: n = 114; ATC: n = 86). To define suitable diagnostic and to screen for putative therapeutic markers, CD56, CD57, CD99, CD117, TTF-1, synaptophysin, chromogranin A, CK 18, KL-1, epidermal growth factor receptor (EGFR), human epidermal growth factor receptor 2 (Her-2/neu), somatostatin receptor subtype 2A (SSTR2A), thymidylate synthase (TS), and excision repair cross-complementation group 1 (ERCC-1) expression was analyzed. A combination of synaptophysin and cytokeratins is the most sensitive marker panel for PC with unclear histomorphology. Predictive phenotyping revealed that SSTR2A is expressed in >80% of all PC and may be used both, as a diagnostic marker for imaging approaches and as a predictive marker for octreotide-based therapies. We introduced a grading system distinguishing between PC with low and highly aggressive biological behavior similar to the grading system for gastrointestinal neuroendocrine tumors. The system is superior to the classical separation into TC and ATC. This study indicates that PI in addition to mitotic count may improve prediction of the biological behavior of PC and should be validated in prospective studies.

[Neuroendocrine neoplasms of the gastrointestinal tract. Classification, clinical presentation and diagnosis]

Neuroendocrine neoplasms of the digestive system represent a rare and heterogeneous group of malignancies with various clinical presentations and prognoses. The WHO classification for the year 2000 was updated in 2010 to take the histopathology and tumor biology of these tumors into account. Together with proliferation-based grading and the recently established staging system using the ENETS TNM classification, it forms the basis for the further diagnostic and therapeutic approach. Clinical presentation depends mainly on the primary site of the tumor and its functionality. Characteristic symptoms are seen only rarely, this being the reason these tumors are usually detected at an advanced stage. Approximately 30% of GEP-NEN are hormonally active and can cause a specific clinical syndrome. In addition to these specific hormones, chromogranin A is considered the most accurate general marker for the biochemical follow-up of these patients. In addition to commonly used radiological and endoscopic imaging modalities, somatostatin receptor-based functional imaging using either octreotide scintigraphy or novel PET-based techniques with specific isotopes such as Ga68-DOTA-octreotate play a crucial role in the detection of the primary tumor as well as in the evaluation of tumor extent and the selection of patients for receptor-based radionuclide therapy.

Overdiagnosis of a typical carcinoid tumor as an adenocarcinoma of the lung: a case report and review of the literature

Background

Overdiagnosis of bronchopulmonary carcinoid tumors together with overtreatment can cause serious postoperative consequences for the patient. We report of a patient with a typical bronchopulmonary carcinoid tumor, which was initially misdiagnosed and treated as an adenocarcinoma of the lung. GnrH receptors and the associated Raf-1/MEK/ERK-1/2-pathway are potential targets for analogs in cancer treatment. We suspected a correlation between the lack of tumor growth, application of leuprolide and the Raf-1/MEK/ERK-1/2-pathway. Therefore, we examined GnrH receptor status in the examined specimen.

Case presentation

In 2010 a 77 year-old male patient was shown to have a tumor mass of about 1.7 cm diameter in the inferior lobe of the left lung. Since 2005, this tumor had hitherto been known and showed no progression in size. The patient suffered from prostate cancer 4 years ago and was treated with TUR-P, radiation therapy and the application of leuprolide. We conducted an explorative thoracotomy with atypical segment resection. The first histological diagnosis was a metastasis of prostate cancer with lymphangiosis carcinomatosa. After several immunohistochemical stainings, the diagnosis was changed to adenocarcinoma of the lung. We conducted a re-thoracotomy with lobectomy and systematic lymphadenectomy 12 days later. The tumor stage was pT1 N0 MX G2 L1 V0 R0. Further immunohistochemical studies were performed. We received the results 15 days after the last operation. The diagnosis was ultimately changed to typical carcinoid tumor without any signs of lymphatic vessel invasion. The patient recovered well from surgery, but still suffers from dyspnea and lack of physical performance. Lung function testing revealed no evidence of impairment.

Conclusion

The use of several immunohistochemical markers, careful evaluation of hematoxylin-eosin sections and the Ki-67 labelling index are important tools in discriminating between carcinoids and other bronchopulmonary carcinomas. Although we could not detect GnrH-receptors in the examined specimen, there may be individual differences in expression. GnrH receptor profiles in typical and atypical carcinoids should be scrutinized. This could lead to new therapeutical options, since the GnrH receptor has already been described on atypical carcinoids. Clinically tested drugs such as leuprolide could come to use.

Mixed Adenoneuroendocrine Carcinomas (MANECs) of the Gastrointestinal Tract: An Update

The systematic application of immunohistochemical techniques to the study of tumors has led to the recognition that neuroendocrine cells occur rather frequently in exocrine neoplasms of the gut. It is now well known that there is a wide spectrum of combinations of exocrine and neuroendocrine components, ranging from adenomas or carcinomas with interspersed neuroendocrine cells at one extreme to classical neuroendocrine tumors with a focal exocrine component at the other. In addition, both exocrine and neuroendocrine components can have different morphological features ranging, for the former, from adenomas to adenocarcinomas with different degrees of differentiation and, for the latter, from well differentiated to poorly differentiated neuroendocrine tumors. However, although this range of combinations of neuroendocrine and exocrine components is frequently observed in routine practice, mixed exocrine-neuroendocrine carcinomas, now renamed as mixed adenoneuroendocrine carcinomas (MANECs), are rare; these are, by definition, neoplasms in which each component represents at least 30% of the lesion. Gastrointestinal MANECs can be stratified in different prognostic categories according to the grade of malignancy of each component. The present paper is an overview of the main clinicopathological, morphological, immunohistochemical and molecular features of this specific rare tumor type.

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.