Neuroendocrine tumors of the lung

Landscape and Treatment Options of Shapeshifting Small Cell Lung Cancer

Small cell lung cancer (SCLC) is a deadly neuroendocrine malignancy, notorious for its rapid tumor growth, early metastasis, and relatively "cold" immune environment. Only standard chemotherapies and a few immune checkpoint inhibitors have been approved for SCLC treatment, revealing an urgent need for novel therapeutic approaches. Moreover, SCLC has been recently recognized as a malignancy with high intratumoral and intertumoral heterogeneity, which explains the modest response rate in some patients and the early relapse. Molecular subtypes defined by the expression of lineage-specific transcription factors (ASCL1, NEUROD1, POU2F3, and, in some studies, YAP1) or immune-related genes display different degrees of neuroendocrine differentiation, immune cell infiltration, and response to treatment. Despite the complexity of this malignancy, a few biomarkers and targets have been identified and many promising drugs are currently undergoing clinical trials. In this review, we integrate the current progress on the genomic landscape of this shapeshifting malignancy, the characteristics and treatment vulnerabilities of each subtype, and promising drugs in clinical phases.

Investigating pulmonary neuroendocrine cells in human respiratory diseases with airway models

Despite accounting for only ∼0.5% of the lung epithelium, pulmonary neuroendocrine cells (PNECs) appear to play an outsized role in respiratory health and disease. Increased PNEC numbers have been reported in a variety of respiratory diseases, including chronic obstructive pulmonary disease and asthma. Moreover, PNECs are the primary cell of origin for lung neuroendocrine cancers, which account for 25% of aggressive lung cancers. Recent research has highlighted the crucial roles of PNECs in lung physiology, including in chemosensing, regeneration and immune regulation. Yet, little is known about the direct impact of PNECs on respiratory diseases. In this Review, we summarise the current associations of PNECs with lung pathologies, focusing on how new experimental disease models, such as organoids derived from human pluripotent stem cells or tissue stem cells, can help us to better understand the contribution of PNECs to respiratory diseases.

Diagnostic challenges in primary ovarian carcinoid: Insights from radiological imaging-A case study

Primary ovarian carcinoid (POC) is a very rare subset of ovarian tumors, presenting diagnostic challenges due to its inconclusive radiological imaging. In this case study, we present a 30-year-old nulliparous female with subfertility complaints and irregular menstrual cycles, who was initially misdiagnosed with an ovarian cyst. Subsequent comprehensive imaging, including Color Doppler, revealed high vascularity, and prompting suspicion of malignancy. Surgical resection and histopathological evaluation ultimately confirmed the presence of a rare Carcinoid tumor, insular type. This case emphasizes a multidisciplinary approach to the early detection and accurate diagnosis of POCs.

2021 WHO Classification of Lung Cancer: Molecular Biology Research and Radiologic-Pathologic Correlation

The 2021 World Health Organization (WHO) classification system for thoracic tumors (including lung cancer) contains several updates to the 2015 edition. Revisions for lung cancer include a new grading system for invasive nonmucinous adenocarcinoma that better reflects prognosis, reorganization of squamous cell carcinomas and neuroendocrine neoplasms, and description of some new entities. Moreover, remarkable advancements in our knowledge of genetic mutations and targeted therapies have led to a much greater emphasis on genetic testing than that in 2015. In 2015, guidelines recommended evaluation of only two driver mutations, ie, epidermal growth factor receptor (EGFR) mutations and anaplastic lymphoma kinase (ALK) fusions, in patients with nonsquamous non-small cell lung cancer. The 2021 guidelines recommend testing for numerous additional gene mutations for which targeted therapies are now available including ROS1, RET, NTRK1-3, KRAS, BRAF, and MET. The correlation of imaging features and genetic mutations is being studied. Testing for the immune biomarker programmed death ligand 1 is now recommended before starting first-line therapy in patients with metastatic non-small cell lung cancer. Because 70% of lung cancers are unresectable at patient presentation, diagnosis of lung cancer is usually based on small diagnostic samples (ie, biopsy specimens) rather than surgical resection specimens. The 2021 version emphasizes differences in the histopathologic interpretation of small diagnostic samples and resection specimens. Radiologists play a key role not only in evaluation of tumor and metastatic disease but also in identification of optimal biopsy targets. ©RSNA, 2024 Test Your Knowledge questions in the supplemental material and the slide presentation from the RSNA Annual Meeting are available for this article.

Two case reports: EML4-ALK rearrangement large cell neuroendocrine carcinoma and literature review

Anaplastic lymphoma kinase gene (ALK) rearrangement is present in only approximately 5% of non-small cell lung cancers (NSCLCs) and is scarce in LCNEC patients. The conventional first-line treatment options are chemotherapy combined with immunotherapy or chemotherapy followed by palliative radiotherapy. In this report, we present two cases of metastatic LCNEC with EML4-ALK fusion that were treated with ALK-TKI inhibitors and demonstrated a rapid therapeutic response. Both patients were nonsmoking women who declined cytotoxic chemotherapy, underwent Next-Generation Sequencing (NGS), and confirmed EML4-ALK fusion. They were treated with alectinib as first-line therapy, and the tumors showed significant shrinkage after two months, achieving a PR (defined as a more than 30% decrease in the sum of maximal dimensions). The PFS was 22 months and 32 months, respectively, until the last follow-up. A systematic review of all previously reported cases of LCNEC with ALK mutations identified only 21 cases. These cases were characterized by being female (71.4%), nonsmoking (85.7%), diagnosed at a relatively young age (median age 51.1), and stage IV (89.5%), with an overall response rate (ORR) of 90.5%. PFS and OS were significantly longer than those treated with conventional chemotherapy/immunotherapy. Based on the clinical characteristics and the effective therapeutic outcomes with ALK inhibitors in LCNEC patients with ALK fusion, we recommend routine ALK IHC (economical, affordable, and convenient, but with higher false positives) as a screening method in advanced LCNEC patients, particularly nonsmoking females or those who are not candidates for or unwilling to undergo cytotoxic chemotherapy. Further molecular profiling is necessary to confirm these potential beneficiaries. We suggest TKI inhibitors as the first-line treatment for metastatic LCNEC with ALK fusion. Additional studies on larger cohorts are required to assess the prevalence of ALK gene fusions and their sensitivity to various ALK inhibitors.

Clinical insights into small cell lung cancer: Tumor heterogeneity, diagnosis, therapy, and future directions

Small cell lung cancer (SCLC) is characterized by rapid growth and high metastatic capacity. It has strong epidemiologic and biologic links to tobacco carcinogens. Although the majority of SCLCs exhibit neuroendocrine features, an important subset of tumors lacks these properties. Genomic profiling of SCLC reveals genetic instability, almost universal inactivation of the tumor suppressor genes TP53 and RB1, and a high mutation burden. Because of early metastasis, only a small fraction of patients are amenable to curative-intent lung resection, and these individuals require adjuvant platinum-etoposide chemotherapy. Therefore, the vast majority of patients are currently being treated with chemoradiation with or without immunotherapy. In patients with disease confined to the chest, standard therapy includes thoracic radiotherapy and concurrent platinum-etoposide chemotherapy. Patients with metastatic (extensive-stage) disease are treated with a combination of platinum-etoposide chemotherapy plus immunotherapy with an anti-programmed death-ligand 1 monoclonal antibody. Although SCLC is initially very responsive to platinum-based chemotherapy, these responses are transient because of the development of drug resistance. In recent years, the authors have witnessed an accelerating pace of biologic insights into the disease, leading to the redefinition of the SCLC classification scheme. This emerging knowledge of SCLC molecular subtypes has the potential to define unique therapeutic vulnerabilities. Synthesizing these new discoveries with the current knowledge of SCLC biology and clinical management may lead to unprecedented advances in SCLC patient care. Here, the authors present an overview of multimodal clinical approaches in SCLC, with a special focus on illuminating how recent advancements in SCLC research could accelerate clinical development.

Masquerading as Pneumonia: A Lung Neuroendocrine Tumor Case Report

The presentation of recurrent pneumonia, particularly in the same lobe, should raise suspicion for possible neuroendocrine tumors of the lung within that respective lobe. Commonly, these types of tumors will have a gastrointestinal origin with a larger incidence of carcinoid syndrome, but they may also originate in the pancreas or lungs. This case illustrates the potential for a masked lung tumor in an otherwise young and healthy 31-year-old patient, with a short history of tobacco dependence and unremarkable family history, who presents with recurrent pneumonia and dyspnea. Although rare in itself, this case was even more unique due to the partial calcification of the neuroendocrine tumor mass along with causing a collapse in the entire right middle lobe.

Washout-Computed Tomography Discriminates Pulmonary "Fat-poor" Hamartomas From Neuroendocrine Neoplasms: A Simple Method in the Radiomics Era

PURPOSE

Pulmonary hamartomas (HAs) and neuroendocrine neoplasms (NENs) are often impossible to discriminate using high-resolution computed tomography (CT) as they share morphologic features. This challenge makes differential diagnosis crucial as HAs are invariably benign, whereas NENs must be considered malignant, thus requiring them to be evaluated for surgical excision.Our aim was, therefore, to develop a simple method to discriminate between pulmonary "fat-poor" HAs and NENs using contrast-enhanced CT (CECT).

MATERIALS AND METHODS

Between September 2015 and December 2021, 95 patients with a histologically proven diagnosis of lung NENs (74) and HAs (21) and who underwent a preoperative CECT scan were initially identified through a review of our pathologic and radiologic databases. Among these, 55 cases (18 HAs and 37 NENs), which have been studied with biphasic CECT, were ultimately selected and reviewed by 3 radiologists with different levels of experience, analyzing their morphologic and enhancement features.The enhancement analysis was performed by placing a region of interest within the lesion in noncontrast (NCp), postcontrast (PCp, 55 to 65 s after intravenous contrast injection), and delayed phases (Dp, 180 to 300 s). A subgroup of 35 patients who underwent 18FDG-PET/CT was evaluated in a secondary analysis.

RESULTS

HU values were significantly different between NENs and HAs in the PCp ( P <0.001). NCp and Dp attenuation values did not show significant differences in the 2 groups. Differences in values of HUs in PCp and Dp allowed to discriminate between NENs and HAs.

CONCLUSION

Wash-out analysis, ΔHU (PCp-Dp), can perfectly discriminate pulmonary "fat-poor" HAs from NENs.

Carcinoid Tumor Presenting as Hemoptysis and Elevated Diaphragm

A bronchial carcinoid tumor is a rare pulmonary neuroendocrine tumor. This report describes a case where a patient experienced multiple episodes of hemoptysis and dyspnea on exertion over the course of five months. An initial chest X-ray showed an elevated right hemidiaphragm with atelectasis, and a follow-up chest computed tomography (CT) scan was ordered to further assess this finding. The CT revealed a tumor occluding 90% of the right main stem bronchus lumen. A bronchoscopy with biopsy was then performed, confirming the diagnosis of a pulmonary carcinoid tumor. The patient underwent surgical resection of the tumor, a right upper lobe sleeve lobectomy, and a mediastinal lymph node dissection, resulting in full eradication of the tumor. This case highlights the need for physicians to maintain a broad differential when evaluating a patient with hemoptysis and an elevated diaphragm.

The uprise of RNA biology in neuroendocrine neoplasms: altered splicing and RNA species unveil translational opportunities

Neuroendocrine neoplasms (NENs) comprise a highly heterogeneous group of tumors arising from the diffuse neuroendocrine system. NENs mainly originate in gastrointestinal, pancreatic, and pulmonary tissues, and despite being rare, show rising incidence. The molecular mechanisms underlying NEN development are still poorly understood, although recent studies are unveiling their genomic, epigenomic and transcriptomic landscapes. RNA was originally considered as an intermediary between DNA and protein. Today, compelling evidence underscores the regulatory relevance of RNA processing, while new RNA molecules emerge with key functional roles in core cell processes. Indeed, correct functioning of the interrelated complementary processes comprising RNA biology, its processing, transport, and surveillance, is essential to ensure adequate cell homeostasis, and its misfunction is related to cancer at multiple levels. This review is focused on the dysregulation of RNA biology in NENs. In particular, we survey alterations in the splicing process and available information implicating the main RNA species and processes in NENs pathology, including their role as biomarkers, and their functionality and targetability. Understanding how NENs precisely (mis)behave requires a profound knowledge at every layer of their heterogeneity, to help improve NEN management. RNA biology provides a wide spectrum of previously unexplored processes and molecules that open new avenues for NEN detection, classification and treatment. The current molecular biology era is rapidly evolving to facilitate a detailed comprehension of cancer biology and is enabling the arrival of personalized, predictive and precision medicine to rare tumors like NENs.

The Importance of the Immune System and Molecular Cell Signaling Pathways in the Pathogenesis and Progression of Lung Cancer

Lung cancer is a disease that in recent years has become one of the greatest threats to modern society. Every year there are more and more new cases and the percentage of deaths caused by this type of cancer increases. Despite many studies, scientists are still looking for answers regarding the mechanisms of lung cancer development and progression, with particular emphasis on the role of the immune system. The aim of this literature review was to present the importance of disorders of the immune system and the accompanying changes at the level of cell signaling in the pathogenesis of lung cancer. The collected results showed that in the process of immunopathogenesis of almost all subtypes of lung cancer, changes in the tumor microenvironment, deregulation of immune checkpoints and abnormalities in cell signaling pathways are involved, which contribute to the multistage and multifaceted carcinogenesis of this type of cancer. We, therefore, suggest that in future studies, researchers should focus on a detailed analysis of tumor microenvironmental immune checkpoints, and to validate their validity, perform genetic polymorphism analyses in a wide range of patients and healthy individuals to determine the genetic susceptibility to lung cancer development. In addition, further research related to the analysis of the tumor microenvironment; immune system disorders, with a particular emphasis on immunological checkpoints and genetic differences may contribute to the development of new personalized therapies that improve the prognosis of patients.

Pulmonary Large Cell Neuroendocrine Carcinoma

Pulmonary large cell neuroendocrine carcinoma (LCNEC) is a rare subtype of malignant pulmonary tumor. The incidence rate of LCNEC was reported to be 0.3%–3% in lung cancers. Although LCNEC is classified as non-small cell lung cancer (NSCLC), it is more aggressive and malignant than other NSCLC, and its biological behavior is similar to that of small cell lung cancer (SCLC). Most of the LCNEC patients are elderly smoking male and the clinical manifestations are not specific. The imaging manifestations of the tumors are often located in the periphery and the upper lobes, and the enlargement of mediastinal or hilar lymph nodes is common. The diagnosis is mainly based on pathology by the histological features and immunohistochemistry (IHC). Specific neuroendocrine markers such as chromogranin A (CgA), synaptophysin (Syn) and CD56 are usually diffusely positive in LCNEC, and found that insulinoma-associated protein (INSM1) and high rate of Ki-67 are helpful for diagnosis. More differential diagnoses also increase the difficulty of correctly diagnosing LCNEC. The rise of LCNEC molecular typing in recent years may be helpful for diagnosis and subsequent treatment. This review focuses on the epidemiological features, imaging studies, pathology, diagnosis, treatment, and prognosis of LCNEC.

Occult Pulmonary Neuroendocrine Tumor Causing Severe Hyperparathyroidism: Diagnostic Challenges and Clinical Outcomes

Background/Objective

Ectopic tumoral production of parathyroid hormone (PTH) is rare. The incidence of hyperparathyroidism and osteitis fibrosa cystica (OFC) secondary to ectopic PTH secretion has only been reported in case reports, although infrequent.

Case Report

We report a case of a well-differentiated pulmonary neuroendocrine tumor (NET) producing PTH that presented with severe hypercalcemia and OFC. Surgical removal of the pulmonary tumor resulted in resolution of hypercalcemia. Immunocytochemical analysis of the tumor tissue revealed PTH-positive staining. Recovery was complicated by severe hypocalcemia due to hungry bone syndrome.

Discussion

To the best of our knowledge, this is the first documented case of a pulmonary NET causing OFC via PTH. We further describe the successful identification and resection of a rare NET and restoration of calcium homeostasis with aggressive calcium and vitamin D repletion.

Conclusion

Although a rare cause of severe hypercalcemia and OFC, ectopic tumoral production of PTH must be considered in the differential diagnosis. Furthermore, resection of these tumors secreting PTH can lead to a protracted and severe high risk of hungry bone syndrome, which requires aggressive treatment to maintain calcium homeostasis.

The Role of Surgery in High-Grade Neuroendocrine Cancer: Indications for Clinical Practice

Pulmonary neuroendocrine tumors (pNET) represent a particular type of malignant lung cancers and can be divided into well-differentiated low-grade NET and poorly-differentiated high-grade NET. Typical and atypical carcinoids belong to the first group while large cell neuroendocrine carcinomas (LCNEC) and small-cell lung cancers (SCLC) belong to the second one. The aim of this mini-review is to focus on the role of surgical therapy for high grade neuroendocrine tumors. SCLC has the worst prognosis among all lung cancer neoplasms: in fact, the two-year survival rate is about 5% and median survival usually ranges between 15 and 20 months. The surgical treatment of SCLC has thus infrequently been judged as a valuable aspect of the therapeutic approach, the gold standard treatment being a combination of platinum-based chemotherapy and radiotherapy. As LCNEC are rare, there is a lack of extensive literature and randomized clinical trials, therefore the curative approach is still controversial. Current treatment guidelines suggest treating LCNEC by surgical resection in non-metastatic stages and recommend adjuvant chemotherapy according to SCLC protocol. Upfront surgery is suggested in early stages (from I to IIB), a multimodality approach is recommended in locally advanced stages (III) while surgery is not recommended in stage IV LCNEC. The rate of surgical resection is quite low, particularly for SCLC, ranging from 1 to 6% in limited diseases; lobectomy with radical lymphadenectomy is considered the gold standard surgical procedure in the case of limited disease SCLC and resectable LCNEC; pneumonectomy, although reported as an effective tool, should be avoided in the light of local and distant recurrence rates.

Primary ovarian carcinoid arising in associated mature cystic teratoma

BACKGROUND

Primary ovarian carcinoid is a very rare ovarian low-grade neuroendocrine tumor, accounting for about 0.1% of all ovarian neoplasms.

CASE PRESENTATION

We reported a case of primary ovarian carcinoid arising from a mature cystic teratoma in a 50-year-old woman. Intraoperative frozen section of left ovarian mass was assessed and a malignant epithelial tumor was considered. Morphologically, the main tumor was composed of cells forming trabeculae, and mature cystic teratoma was observed adjacent to the main part. Immunohistochemistry revealed that the trabecular cells were diffuse positive for pan Cytokeratin, CD56 and synaptophysin with low Ki-67 index (about 1%).

CONCLUSIONS

Careful morphological observation combined with appropriate accessory examination are essential for the diagnosis of primary ovarian carcinoid arising from mature cystic teratoma. In addition, the classification criteria of the primary ovarian neuroendocrine tumor are discussed.

Serum NSE is Early Marker of Transformed Neuroendocrine Tumor After EGFR-TKI Treatment of Lung Adenocarcinoma

Background

Transformation to a lung neuroendocrine tumor (LNET) is a mechanism of resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKI). Serum neuron-specific enolase (NSE) is a useful marker in the detection of LNET. Therefore, we explored the clinical significance of serum NSE levels in the detection of transformed neuroendocrine tumors after EGFR-TKI therapy.

Methods

We report a cohort of 5 cases in our treatment group. The characteristics of the patients, pathological diagnoses, immunohistochemistry with molecular detection, laboratory examination, and treatment histories are analyzed. The tumor markers of serum NSE were analyzed. Additionally, we reviewed the publications reporting the tumor markers before and after LNET transformation during EGFR-TKI therapy.

Results

Most patients are female (3/5), aged <60 years old (4/5), nonsmokers (4/5) and harbor the EGFR 19 exon deletion (4/5). The median time of LNET transformation was 19 months (range: 12–31 months). The clinical characteristics were similar to those reported in previous studies. Laboratory examination revealed an increased NSE level before the LNET is defined. Sixteen publications were reviewed. Of those, 86.67% (13/15) publications showed an increased level of NSE when the LNET transformation was defined.

Conclusion

Adenocarcinoma tumors in non-smokers, young patients harboring the EGFR 19 exon deletion tended to transform to LNETs after EGFR-TKI therapy. Combining our findings and a review of the literature, we suggest that serum NSE may be a useful tumor marker to predict neuroendocrine tumor transformation.

Differential diagnostic value of 18F-FDG PET/CT in pulmonary carcinoids versus hamartomas

RATIONALE AND OBJECTIVE

To assess the possibility of differentiating pulmonary carcinoids from hamartomas and typical from atypical carcinoids by means of ¹⁸F-FDG PET/CT.

MATERIALS AND METHODS

We retrospectively reviewed 139 patients with pathologically proven pulmonary carcinoids and hamartomas who underwent ¹⁸F-FDG PET/CT before surgical resection. Receiver operating characteristics curves were calculated to determine the potential of SUVmax to discriminate between pulmonary carcinoids and hamartomas, typical and atypical carcinoids. The correlation between SUVmax and tumor size was analyzed by Spearman correlation analysis.

RESULTS

SUVmax was significantly higher in pulmonary carcinoids than in hamartomas (p<0.001), and also higher in atypical carcinoids than in typical carcinoids (p = 0.034). With a SUVmax of 2.0 as a cutoff, the sensitivity, specificity, positive predictive value, and negative predictive value for ¹⁸F-FDG PET/CT to differentiate pulmonary carcinoids from hamartomas were 85.3%, 82.9%, 61.7%, and 94.6%, respectively. The cutoff value of SUVmax for differentiating atypical carcinoids from typical carcinoids was 4.1. The area under the receiver operating characteristics curve of SUVmax was 0.900 for carcinoids and hamartomas, and 0.722 for typical and atypical carcinoids. SUVmax was correlated with maximum tumor size in pulmonary carcinoids (r = 0.658, p <0.001) and in pulmonary hamartomas (r = 0.672, p <0.001).

CONCLUSION

¹⁸F-FDG PET/CT might be a useful tool in the differential diagnosis of carcinoids and hamartomas, and can also distinguish atypical from typical carcinoids. This may facilitate improved selection of patients for surgical resection and radiological follow-up.

Endocrine secretory granule production is caused by a lack of REST and intragranular secretory content and accelerated by PROX1

Endocrine secretory granules (ESGs) are morphological characteristics of endocrine/neuroendocrine cells and store peptide hormones/neurotransmitters. ESGs contain prohormones and ESG-related molecules, mainly chromogranin/secretogranin family proteins. However, the precise mechanism of ESG formation has not been elucidated. In this study, we experimentally induced ESGs in the non-neuroendocrine lung cancer cell line H1299. Since repressive element 1 silencing transcription factor (REST) and prospero homeobox 1 (PROX1) are closely associated with the expression of ESG-related molecules, we edited the REST gene and/or transfected PROX1 and then performed molecular biology, immunocytochemistry, and electron and immunoelectron microscopy assays to determine whether ESG-related molecules and ESGs were induced in H1299 cells. Although chromogranin/secretogranin family proteins were induced in H1299 cells by knockout of REST and the induction was accelerated by the PROX1 transgene, the ESGs could not be defined by electron microscopy. However, a small number of ESGs were detected in the H1299 cells lacking REST and expressing pro-opiomelanocortin (POMC) by electron microscopy. Furthermore, many ESGs were produced in the REST-lacking and PROX1- and POMC-expressing H1299 cells. These findings suggest that a lack of REST and the expression of genes related to ESG content are indispensable for ESG production and that PROX1 accelerates ESG production.

Trial registration: Not applicable.

DNA-methylation patterns imply a common cellular origin of virus- and UV-associated Merkel cell carcinoma

Merkel cell carcinoma (MCC) is a neuroendocrine tumor either induced by integration of the Merkel cell polyomavirus into the cell genome or by accumulation of UV-light-associated mutations (VP-MCC and UV-MCC). Whether VP- and UV-MCC have the same or different cellular origins is unclear; with mesenchymal or epidermal origins discussed. DNA-methylation patterns have a proven utility in determining cellular origins of cancers. Therefore, we used this approach to uncover evidence regarding the cell of origin of classical VP- and UV-MCC cell lines, i.e., cell lines with a neuroendocrine growth pattern (n = 9 and n = 4, respectively). Surprisingly, we observed high global similarities in the DNA-methylation of UV- and VP-MCC cell lines. CpGs of lower methylation in VP-MCC cell lines were associated with neuroendocrine marker genes such as SOX2 and INSM1, or linked to binding sites of EZH2 and SUZ12 of the polycomb repressive complex 2, i.e., genes with an impact on carcinogenesis and differentiation of neuroendocrine cancers. Thus, the observed differences appear to be rooted in viral compared to mutation-driven carcinogenesis rather than distinct cells of origin. To test this hypothesis, we used principal component analysis, to compare DNA-methylation data from different epithelial and non-epithelial neuroendocrine cancers and established a scoring model for epithelial and neuroendocrine characteristics. Subsequently, we applied this scoring model to the DNA-methylation data of the VP- and UV-MCC cell lines, revealing that both clearly scored as epithelial cancers. In summary, our comprehensive analysis of DNA-methylation suggests a common epithelial origin of UV- and VP-MCC cell lines.

Recent Advances in the Diagnosis and Management of Carcinoid Syndrome

Carcinoid syndrome, a paraneoplastic condition linked with the release of multiple humoral factors, affects around 30-40% of patients with well-differentiated neuroendocrine tumours. Carcinoid syndrome has a major and unfavourable impact on patients' quality of life; it raises costs when compared to non-functioning neuroendocrine tumours; and it causes patients' lifestyles to alter, such as food, job, physical activity, and social life. Somatostatin analogues have been the first-line therapy for individuals with neuroendocrine tumours and carcinoid disease for decades. While these drugs give considerable relief from carcinoid syndrome symptoms, clinical progression is unavoidable, necessitating further research into newer treatment measures. Carcinoid tumours are sometimes difficult to diagnose because of their vague or nonspecific symptoms. There have been several advancements in all aspects of carcinoid syndrome, as well as novel therapeutics, in the previous few years. New epidemiological studies show that it is becoming more common; increasing insights into the pathogenesis of its various clinical manifestations and its natural history: definition of prognostic factors; new methods to verify its presence; the development of new drugs to treat its various manifestations, both initially and in somatostatin-refractory cases; and an increased understanding of the pathogenesis, natural history, and management of the disease. An all language literature search was conducted on MEDLINE, COCHRANE, EMBASE, and Google Scholar till November 2021. The following search strings and Medical Subject Headings (MeSH) terms were used: "Recent advances", "Carcinoid syndrome", "Neuroendocrine Neoplasms" and "Carcinoid heart disease". We comprehensively reviewed the literature on the pathogenesis, clinical features, and newer treatment modalities for Carcinoid Syndrome. Recent advancements in research and management have resulted from advances in our understanding of the aetiology of carcinoid syndrome. The development of molecular indicators of aggressiveness improved serum tumour markers, and the molecular aetiology of carcinoid heart disease are all possible because of advances in molecular biology. We conducted a comprehensive review to update knowledge regarding the pathophysiology, diagnostic protocols, and current and newer treatments for carcinoid syndrome, which presently requires a multidisciplinary approach, due to the complexity of the illness's aetiology, diagnosis, and therapy.

A review on epidermal growth factor receptor's role in breast and non-small cell lung cancer

Epithelial growth factor receptor (EGFR) is a cell surface transmembrane receptor that mediates the tyrosine signaling pathway to carry the extracellular messages inside the cell and thereby alter the function of nucleus. This leads to the generation of various protein products to up or downregulate the cellular function. It is encoded by cell erythroblastosis virus oncogene B1, so called C-erb B1/ERBB2/HER-2 gene that acts as a proto-oncogene. It belongs to the HER-2 receptor-family in breast cancer and responds best with anti-Herceptin therapy (anti-tyrosine kinase monoclonal antibody). HER-2 positive breast cancer patient exhibits worse prognosis without Herceptin therapy. Similar incidence and prognosis are reported in other epithelial neoplasms like EGFR + lung non-small cell carcinoma and glioblastoma (grade IV brain glial tumor). Present study highlights the role and connectivity of EGF with various cancers via signaling pathways, cell surface receptors mechanism, macromolecules, mitochondrial genes and neoplasm. Present study describes the EGFR associated gene expression profiling (in breast cancer and NSCLC), relation between mitrochondrial genes and carcinoma, and several in vitro and in vivo models to screen the synergistic effect of various combination treatments. According to this study, although clinical studies including targeted treatments, immunotherapies, radiotherapy, TKi-EGFR combined targeted therapy have been carried out to investigate the synergism of combination therapy; however still there is a gap to apply the scenarios of experimental and clinical studies for further developments. This review will give an idea about the transition from experimental to most advanced clinical studies with different combination drug strategies to treat cancer.

Alveolar progenitor cells and the origin of lung cancer

Lung Cancer is the leading cause of cancer-related deaths worldwide. This is mainly due to late diagnosis and therefore advanced stage of the disease. Understanding the cell of origin of cancer and the processes that lead to its transformation will allow for earlier diagnosis and more accurate prediction of tumour type, ultimately leading to better treatments and lower patient morbidity. In this review, we focus on alveolar type 2 (AT2) cells as the cell of origin of lung adenocarcinoma (LUAD), the most common type of lung cancer. We first elaborate on the different oncogenes that are associated with LUAD and other lung cancers. After, we lay out in detail what is known about AT2 biology, to further delve into AT2 cells as cell of origin for adenocarcinoma. Understanding the precursors of LUAD and identifying the molecular changes during its progression will allow for earlier detection and better molecular targeting of the disease in early stages.

Multiple endocrine neoplasia type 1 (MEN-1) and neuroendocrine neoplasms (NENs)

Neuroendocrine neoplasms (NENs) are relatively rare neoplasms with 6.4-times increasing age-adjusted annual incidence during the last four decades. NENs arise from neuroendocrine cells, which release hormones in response to neuronal stimuli and they are distributed into organs and tissues. The presentation and biological behaviour of the NENs are highly heterogeneous, depending on the organ. The increased incidence is mainly due to increased awareness and improved detection methods both in the majority of sporadic NENs (non-inherited), but also the inherited groups of neoplasms appearing in at least ten genetic syndromes. The most important one is multiple endocrine neoplasia type 1 (MEN-1), caused by mutations in the tumour suppressor gene MEN1. MEN-1 has been associated with different tumour manifestations of NENs e.g. pancreas, gastrointestinal tract, lungs, thymus and pituitary. Pancreatic NENs tend to be less aggressive when arising in the setting of MEN-1 compared to sporadic pancreatic NENs. There have been very important improvements over the past years in both genotyping, genetic counselling and family screening, introduction and validation of various relevant biomarkers, as well as newer imaging modalities. Alongside this development, both medical, surgical and radionuclide treatments have also advanced and improved morbidity, quality of life and mortality in many of these patients. Despite this progress, there is still space for improving insight into the genetic and epigenetic factors in relation to the biological mechanisms determining NENs as part of MEN-1. This review gives a comprehensive update of current evidence for co-occurrence, diagnosis and treatment of MEN-1 and neuroendocrine neoplasms and highlight the important progress now finding its way to international guidelines in order to improve the global management of these patients.

Incidence and Survival Outcomes in Patients with Lung Neuroendocrine Neoplasms in the United States

BACKGROUND

The incidence and prevalence of neuroendocrine neoplasms (NENs) are rapidly rising. Epidemiologic trends have been reported for common NENs, but specific data for lung NENs are lacking.

METHODS

We conducted a retrospective analysis utilizing the Surveillance, Epidemiology, and End Results (SEER) database. Associated population data were utilized to report the annual age-adjusted incidence and overall survival (OS) trends. Trends for large-cell neuroendocrine carcinoma (LCNEC) and atypical carcinoid (AC) were reported from 2000-2015, while those for typical carcinoid (TC) and small cell lung cancer (SCLC) were reported from 1988-2015.

RESULTS

We examined a total of 124,969 lung NENs [103,890-SCLC; 3303-LCNEC; 8146-TC; 656-AC; 8974-Other]. The age-adjusted incidence rate revealed a decline in SCLC from 8.6 in 1988 to 5.3 in 2015 per 100,000; while other NENs showed an increase: TC increased from 0.57 in 1988 to 0.77 in 2015, AC increased from 0.17 in 2001 to 0.22 in 2015, and LCNEC increased from 0.16 in 2000 to 0.41 in 2015. The 5-year OS rate among SCLC, LCNEC, AC, and TC patients was 5%, 17%, 64%, and 84%, respectively. On multivariable analyses, OS and disease-specific survival (DSS) varied significantly by stage, sex, histological type, insurance type, marital status, and race, with a better survival noted in earlier stages, females, married, insured, Hispanic and other races, and urban population. Similarly, TC and AC had better survival compared to SCLC and LCNEC.

CONCLUSION

The incidence of lung NENs is rising, possibly in part because of advanced radiological techniques. However, the incidence of SCLCs is waning, likely because of declining smoking habits. Such population-based studies are essential for resource allocation and to prioritize future research directions.

CHALLENGES OF AN OVARIAN NEUROENDOCRINE METASTASIS OF ADVANCED SMALL-CELL LUNG CARCINOMA - LITERATURE REVIEW AND CASE REPORT

Metastatic tumors account for 5-10% of all ovarian malignancies. They are usually bilateral tumors with a multinodular surface and extensive extra ovarian spread. Lung cancer is a rare source (0.3% of metastatic ovarian tumors). Among synchronous primary cancers, ovarian cancer is most frequently associated with endometrial cancer. The differential diagnosis between a primary ovarian carcinoma, synchronous primary cancers, and metastatic ovarian carcinoma is very important, as the treatment and prognosis are markedly different. We report the case of a 25-year-old woman who had been diagnosed and treated for stage IIIB small cell lung carcinoma (SCLC). Imaging undertaken for abdominal pain revealed a unilateral 8.5 cm ovarian tumor for which adnexectomy was performed. Histology and immunohistochemistry led to the diagnosis of ovarian metastasis from SCLC, a high-grade neuroendocrine lung tumor. This patient's particular features, all infrequent in a metastatic tumor, are the lesion's unilaterality (atypical for ovarian metastases in other cancers, but often observed in SCLC), the smooth ovarian surface with intact capsule, and the absence of intra-abdominal dissemination. The patient developed liver and vertebral metastases. This report focuses on the differential diagnosis between primary and metastatic ovarian neoplasms. We performed an extensive search of the literature on SCLC and ovarian metastases. Immunohistochemistry is essential for diagnosis when imaging and the pathological evaluation of the ovarian tumor cannot make the differential diagnosis.

Clinical implications of lung neuroendocrine neoplasm classification

INTRODUCTION

Neuroendocrine neoplasms of the lung (Lung NENs) encompass NE tumors (NETs), which are in turn split into typical and atypical carcinoids, and NE carcinomas (NECs), which group together small-cell carcinoma and large-cell NE carcinoma. This classification is the current basis for orienting the daily practice of these patients, with diagnostic, prognostic, and predictive inferences.

AREAS COVERED

The clinical implications of lung NEN classification are addressed according to three converging perspectives, which were dissected through an extensive literature overview: (1) how to put intratumor heterogeneity into the context of the current classification; (2) how to contextualize immunohistochemistry markers to improve diagnosis, prognosis, and therapy prediction; and (3) how to use immuno-oncology strategies for life-threatening NECs, which still account for 90% or more of lung NENs.

EXPERT OPINION

We provide practical insights to account for intratumor heterogeneity, practice the choice of immunohistochemistry markers, and emphasize once again the added value of immuno-oncology in the setting of personalized medicine of lung NENs.

Recent Advances in the Management of Typical and Atypical Lung Carcinoids

Neuroendocrine neoplasms of the lung represent about 20% to 30% of all neuroendocrine tumors. On the basis of clinical and pathologic characteristics, 2 different categories of tumors may be defined: poorly differentiated neuroendocrine neoplasms, characterized by a high rate of recurrences and poor prognosis, and well-differentiated neuroendocrine neoplasms (typical carcinoids and atypical carcinoids), which generally display an indolent course. Lung carcinoids represent only 1% to 5% of all lung malignancies, but their incidence has significantly increased over the past 30 years. Surgery is the reference standard of treatment for lung carcinoids with locoregional disease. For advanced or unresectable lung carcinoids, several therapeutic options are available, but the choice should be shared within a multidisciplinary team to ensure optimal therapeutic outcomes. We describe the current management of these rare neoplasms.

Less Is More: Rare Pulmonary Neuroendocrine Cells Function as Critical Sensors in Lung

Pulmonary neuroendocrine cells (PNECs) are rare airway epithelial cells that also uniquely harbor neuronal and endocrine characteristics. In vitro data indicate that these cells respond to chemical or mechanical stimuli by releasing neuropeptides and neurotransmitters, implicating them as airway sensors. Emerging in vivo data corroborate this role and demonstrate that PNECs are important for lung response to signals, such as allergens. With close proximity to steady-state immune cells and innervating nerves, PNECs, as prototype tissue-resident neuroendocrine cells, are at the center of a neuro-immune module that enables the fundamental ability of an organ to sense and respond to the environment.

Therapeutic options in lung neuroendocrine tumors: between established concepts and new hopes

Typical (TC) and atypical (AC) carcinoids are low-grade neuroendocrine tumors (NETs) of the lung and, are neglected diseases in respect of both high-grade NETs of the lung (i.e. small-cell lung cancer and large-cell neuroendocrine carcinoma) and gastroenteropancreatic (GEP)-NETs. AC and TC account for 2 and 0.2% of all thoracic malignancies, respectively, and have a 12.9% chance of metastatic spread at diagnosis, reaching up to 20% during disease history. There are very few trials specifically designed for lung NETs, and therapeutic options are mainly derived by studies carried out in patients with GEP-NETs. We report a case of a patient affected by AC progressed to available standard treatments who received off-label treatment with sunitinib, a well-known multitarget tyrosine-kinase inhibitor with marked antiangiogenic activity, used routinely for the treatment of GEP-NETs. During treatment, the patient required the administration of an alternative schedule to improve tolerability, with benefit, and achieved a partial response according to the RECIST criteria, which is unusual in NETs. We critically reviewed available data supporting the use of somatostatin analogs, chemotherapy, and target therapies (everolimus and sunitinib) in advanced lung NETs. In the review, ongoing trials in lung NETs and future developments in this research field are also discussed.

Pulmonary Neuroendocrine Tumor Presenting as a Left Pleural Effusion

The presence of a symptomatic and recurrent unilateral pleural effusion should alert physicians to consider thoracentesis with mindful use of biomarkers not only for therapeutic purposes, but also for diagnosis of both benign and malignant etiologies.

Carcinoid Syndrome: A Review

Carcinoid syndrome (CS) is a paraneoplastic syndrome caused by the release of serotonin and other substances from well-differentiated neuroendocrine tumors (NETs). The hallmark symptoms of carcinoid syndrome are flushing and diarrhea; atypical signs and symptoms can include wheezing, abdominal pain, valvular heart disease, telangiectasias, pellagra, and the complications of mesenteric fibrosis, including ureteral obstruction, bowel obstruction, and bowel ischemia. These symptoms are mediated by the release of serotonin (5-HT), histamine, kallikrein, prostaglandins, and tachykinins. The diagnosis of CS requires these symptoms and corresponding elevations in lab tests. Treatment options include surgery and medical management with somatostatin analogs.

The "numb chin syndrome": A case report

INTRODUCTION

Neuroendocrine tumours comprise 0.5-2% of all malignancies in adulthood, and very rarely metastasize to the oral cavity. When they do metastasize to the oral cavity, the mandible is the most common site. This can lead to symptoms such as a numb chin and lip, which in the absence of any odontogenic cause may be an important sign indicating malignant disease. We present a rare case of metastatic neuroendocrine carcinoma to the mandible, resulting in the so-called "numb chin syndrome".

PRESENTATION OF CASE

An elderly lady presented with numbness to the right chin and lip, as well as hypoglossal nerve palsy. She had significant back pain and gave a history of repeat chest infections. Intra-oral clinical examination was normal, but upon further special investigations, the right mental region was suspicious of multiple lytic lesion. Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) demonstrated marrow changes in the mandible suspicious of malignant disease. Further findings included multiple pathological fractures of the spine and a mass in the left lung base. A trephine biopsy gave a diagnosis of metastatic neuroendocrine carcinoma, with the left lung mass considered to be the primary site.

DISCUSSION

We discuss the rarity of metastatic disease to the oral cavity, and the importance of "numb chin syndrome" in indicating malignancy.

CONCLUSIONS

This case promotes the importance of considering sinister pathology when presented with sudden, altered sensation to the chin and lips. The "numb chin syndrome" should always raise the suspicion of primary or metastatic disease to the mandible.

Epithelial cell plasticity defines heterogeneity in lung cancer

Lung cancer is the leading cause of cancer death for both men and women and accounts for almost 18.4% of all deaths due to cancer worldwide, with the global incidence increasing by approximately 0.5% per year. Lung cancer is regarded as a devastating type of cancer owing to its high prevalence, reduction in the health-related quality of life, frequently delayed diagnosis, low response rate, high toxicity, and resistance to available therapeutic options. The highly heterogeneous nature of this cancer with a proximal-to-distal distribution throughout the respiratory tract dramatically affects its diagnostic and therapeutic management. The diverse composition and plasticity of lung epithelial cells across the respiratory tract are regarded as significant factors underlying lung cancer heterogeneity. Therefore, definitions of the cells of origin for different types of lung cancer are urgently needed to understand lung cancer biology and to achieve early diagnosis and develop cell-targeted therapies. In the present review, we will discuss the current understanding of the cellular and molecular alterations in distinct lung epithelial cells that result in each type of lung cancer.

Lung Carcinoma Presenting as a Superior Vena Cava Syndrome, Burnt and Twice Reborn as Adrenal and Facial Tumors

Eighty-five percent of all lung cancers are Non-Small-Cell Lung Carcinoma (NSCLC) with common sites of metastasis to the adrenal glands and liver. Onset is insidious, and seventy-five percent of patients have either regional or distant metastases at initial presentation. The five-year relative survival rate is four and a half percent with a distantly spread disease based on recent studies. Here we present a unique case of a ten-year survival with NSCLC initially presenting as a Superior Vena Cava Syndrome and reoccurring with adrenal gland, bone, and CNS lesions. The patient presented with SVC caused by lung cancer and underwent chemo and radiotherapy with complete response in 2010. Five years later, the same cancer returned disguised as an adrenal tumor. In 2017, the patient came in with facial neuropathy, shooting pains, sinus headaches, eyelid concerns, and active tumoral activity was detected in the middle cranial fossa, involving parotid glands and the vertebral column. Craniotomy revealed a metastatic poorly differentiated adenocarcinoma that extended through foramen ovale and rotundum to the infratemporal fossa and caused left-sided facial paralysis, hearing loss and numbness in CN V2 - V3 distribution. Considering that the patient has experienced several recurrences of disease on standard protocols and is not a candidate for targeted molecular therapies, an immunotherapy trial was suggested as the next step. The natural history of this disease is remarkable in terms of metastatic sites, paraneoplastic manifestations, and a substantially prolonged lifespan. Thus, more studies of similar cases will advance our understanding of tumor genetics and immunotherapy allowing the greater benefit to future patients.

High FA2H and UGT8 transcript levels predict hydroxylated hexosylceramide accumulation in lung adenocarcinoma

Lung cancer causes more deaths than any other cancer. Sphingolipids encompass metabolically interconnected species whose balance has pivotal effects on proliferation, migration, and apoptosis. In this study, we paralleled quantification of sphingolipid species with quantitative (q)PCR analyses of metabolic enzymes in order to identify dysregulated routes of sphingolipid metabolism in different subtypes of lung cancers. Lung samples were submitted to histopathological reexamination in order to confirm cancer type/subtype, which included adenocarcinoma histological subtypes and squamous cell and neuroendocrine carcinomas. Compared with benign lesions and tumor-free parenchyma, all cancers featured decreased sphingosine-1-phosphate and SMs. qPCR analyses evidenced differential mechanisms leading to these alterations between cancer types, with neuroendocrine carcinomas upregulating SGPL1, but CERT1 being downregulated in adenocarcinomas and squamous cell carcinomas. 2-Hydroxyhexosylceramides (2-hydroxyHexCers) were specifically increased in adenocarcinomas. While UDP-glycosyltransferase 8 (UGT8) transcript levels were increased in all cancer subtypes, fatty acid 2-hydroxylase (FA2H) levels were higher in adenocarcinomas than in squamous and neuroendocrine carcinomas. As a whole, we report differing mechanisms through which all forms of lung cancer achieve low SM and lysosphingolipids. Our results also demonstrate that FA2H upregulation is required for the accumulation of 2-hydroxyHexCers in lung cancers featuring high levels of UGT8.

Role of Immunocytochemistry in the Cytological Diagnosis of Pulmonary Tumors

Pulmonary cytology is a challenging diagnostic tool, and it is usually evaluated considering medical history and radiological findings in order to reach an accurate diagnosis. Since the majority of lung cancer patients have an advanced stage at diagnosis, a cytological specimen is frequently the only material available for diagnosis and further prognostic/predictive marker determination. Several types of specimens can be obtained from the respiratory system (including sputum, bronchoalveolar lavage, bronchial brushing, fine needle aspiration, and pleural fluid) with different technical preclinical management protocols and different diagnostic yields. Immunocytochemistry (ICC) has a pivotal role in the determination of diagnostic, prognostic, and predictive markers. Therefore, limited cytology samples are to be used with a cell-sparing approach, to allow both diagnostic ICC evaluation as well as predictive marker assessment by ICC or specific molecular assays. In this review, we describe the most common ICC markers used for the diagnosis and prognostic/predictive characterization of thoracic tumors in different cytological specimens.

The 4Ds of ectopic ACTH syndrome: diagnostic dilemmas of a difficult disease

Cushing's syndrome (CS) is an uncommon condition that leads to high morbidity and mortality. The majority of endogenous CS is caused by excessive ACTH secretion, mainly due to a pituitary tumor - the so-called Cushing's disease (CD) - followed by ectopic ACTH syndrome (EAS), an extra-pituitary tumor that produces ACTH; adrenal causes of CS are even rarer. Several methods are used to differentiate the two main etiologies: specific laboratory tests and imaging procedures, and bilateral inferior petrosal sinus sampling (BIPSS) for ACTH determination; however, identification of the source of ACTH overproduction is often a challenge. We report the case of a 28-year-old woman with clinical and laboratory findings consistent with ACTH-dependent CS. All tests were mostly definite, but several confounding factors provoked an extended delay in identifying the origin of ACTH secretion, prompting a worsening of her clinical condition, with difficulty controlling hyperglycemia, hypokalemia, and hypertension. During this period, clinical treatment was decisive, and measurement of morning salivary cortisol was a differential for monitoring cortisol levels. This report shows that clinical reasoning, experience and use of recent methods of nuclear medicine were decisive for the elucidation of the case.

Large Cell Neuroendocrine Carcinoma Shares Similarity with Small Cell Carcinoma on the Basis of Clinical and Pathological Features

BACKGROUND: Large cell neuroendocrine carcinoma (LCNEC) was categorized into pulmonary neuroendocrine tumors (NETs) according to the World Health Organization classification guideline. However, LCNEC patients often received the chemotherapy regimens similar to non-small cell lung carcinoma (NSCLC) in advanced stage and the therapeutic effect was unsatisfactory. Therefore, this study aimed to investigate the hidden clinical features, prognosis and immunoprofile of the LCNEC, compared with carcinoid and SCLC, to explore whether LCNEC shares similarity with SCLC and potential treatment approaches could be revealed. METHODS: One hundred seventeen pulmonary NETs cases were retrospectively retrieved in this study. The Kaplan–Meier estimator was employed to draw survival curves. Immunohistochemistry was applied to detect NET-related markers expression. RESULTS: In clinical features, compared with carcinoid, LCNEC patients were older, more commonly in male and advanced stage. The parallel phenomena were also found in the high-grade subgroup when compared with the low- to intermediate-grade one. In survival analysis, the 5-year overall survival of LCNECs was 59.1%, which was poorer than that of carcinoids, but better than that of SCLCs. Immunohistochemistry showed that p53 and PTEN functional inactivation, up-regulation of CD117 expression, down-regulation of SSR2A and SSR5 expression were commonly involved in LCNECs when compared with carcinoids, or in the high-grade subgroup when compared with the low- to intermediate-grade one. However, no significant difference was found in the comparison between LCNECs and SCLCs, or NSCLCs and SCLCs. CONCLUSION: In clinical features, survival and immunoprofile, LCNEC showed more similarity with SCLC rather than carcinoid, which might guide novel therapy for pulmonary NETs.

Paraneoplastic syndromes: Definitions, classification, pathophysiology and principles of treatment

Paraneoplastic syndromes (PNS) are rare clinical syndromes due to the systemic effects of tumours; they are unrelated to tumour size, invasiveness or metastases. Recent years have seen considerable advances leading to improved understanding of their pathophysiology and increased recognition of new PNS entities and PNS associated tumours. While of paramount importance, diagnosis is still frequently missed or delayed. Diverse organs and systems are affected by the associated tumours- which may be benign or malignant. PNS can occur concurrently with tumour diagnosis, before tumour is diagnosed and even after tumours have been resected. Also, there are autoimmune diseases later progressing to PNS when occult tumours are identified. Another confounding factor is that many PNS clinically resemble non-neoplastic diseases. PNS are largely due to two main causes: those due to tumour secretions of hormones, functionally active peptides, enzymes cytokines or to tumours operating through auto-immune/immunological mechanisms with cross-reacting antibodies between neoplastic and normal tissues. Remission of symptoms often follows resection of humoral secretory tumours but not always of tumours due to immunological mechanisms. Classifications schemes vary but most currently place PNS in one of five groups: endocrine, neurological, musculocutaneous, haematological and other. Due to advances both in diagnostic techniques in identifying tumours as well as in therapy, early diagnosis not only results in improved prognosis of both PNS and associated tumours but also enables monitoring response to treatment and early detection of recurrence. This article covers definition, general principals of classification, diagnosis, pathophysiology and treatment, with emphasis on tumour related PNS serving as an introduction to the following articles.

Consider the lung as a sensory organ: A tip from pulmonary neuroendocrine cells

While the lung is commonly known for its gas exchange function, it is exposed to signals in the inhaled air and responds to them by collaborating with other systems including immune cells and the neural circuit. This important aspect of lung physiology led us to consider the lung as a sensory organ. Among different cell types within the lung that mediate this role, several recent studies have renewed attention on pulmonary neuroendocrine cells (PNECs). PNECs are a rare, innervated airway epithelial cell type that accounts for <1% of the lung epithelium population. They are enriched at airway branch points. Classical in vitro studies have shown that PNECs can respond to an array of aerosol stimuli such as hypoxia, hypercapnia and nicotine. Recent in vivo evidence suggests an essential role of PNECs at neuroimmunomodulatory sites of action, releasing neuropeptides, neurotransmitters and facilitating asthmatic responses to allergen. In addition, evidence supports that PNECs can function both as progenitor cells and progenitor niches following airway epithelial injury. Increases in PNECs have been documented in a large array of chronic lung diseases. They are also the cells-of-origin for small cell lung cancer. A better understanding of the specificity of their responses to distinct insults, their impact on normal lung function and their roles in the pathogenesis of pulmonary ailments will be the next challenge toward designing therapeutics targeting the neuroendocrine system in lung.

Advanced typical and atypical carcinoid tumours of the lung: management recommendations

Background

Neuroendocrine tumours (nets) are classified by site of origin, with lung being the second most common primary site after the gastrointestinal tract. Lung nets are rare and heterogeneous, with varied pathologic and clinical features. Typical and atypical carcinoid tumours are low-grade lung nets which, compared with the more common high-grade nets, are associated with a more favourable prognosis. Still, optimal treatment strategies are lacking.

Methods

This review concentrates on classification and treatment strategies for metastatic low-grade lung nets, considering both typical and atypical carcinoids. The terminology can be confusing, and an attempt is made to simplify it. Promising results from recent trials that included lung nets are presented and discussed. Finally, guidelines from Europe and North America are discussed, and differences are noted.

Results

Even within the group of patients with low-grade nets, the presentation, the locations of metastasis, and the speed of progression can be very different. The initial work-up and an understanding of the tumour's biology are key in making management decisions. Various treatment options-including somatostatin analogs, peptide receptor radioligand therapy, and biologic systemic therapy, specifically with the mtor (mechanistic target of rapamycin) inhibitor everolimus-are now available and are presented in a treatment algorithm.

Summary

Although lung nets are rare and evidence supporting optimal treatment strategies is lacking, the recent publication of trials that have included patients with lung nets advances evidence-based therapy for these tumours. Many variables have to be considered in managing these tumours that have received little attention. Education for treating physicians is needed.

HPV-related Oropharyngeal Carcinoma: A Review of Clinical and Pathologic Features With Emphasis on Updates in Clinical and Pathologic Staging

There has been a sharp increase in the incidence of the human papilloma virus-related oropharyngeal squamous cell carcinoma, partly due to the increasingly widespread awareness and recognition of this entity. This review assimilates the recent histopathologic classifications, staging systems, rapidly expanding research base and developments in management of human papilloma virus-related oropharyngeal squamous cell carcinoma and summarizes their implications for routine diagnostic practice. Differential diagnoses and their cytologic appearances are detailed and the utility of p16 staining and other immunohistochemistry testing is discussed.

Neuroendocrine Neoplasia in Extranodal Marginal Zone Lymphoma of Mucosa-Associated Lymphoid Tissue (MALT Lymphoma) of the Lung: A Case Report and Immunohistochemistry Analysis of Eight Pulmonary MALT Lymphomas

Carcinoid tumorlets are peribronchiolar proliferations of neuroendocrine cells often associated with lung scars. Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) is a non-Hodgkin's lymphoma that frequently involves the gastrointestinal tract but less commonly is described in the lung. Simultaneous occurrence of neuroendocrine neoplasms and MALT lymphoma is extraordinarily rare and has predominately been reported in the gastrointestinal tract. In this article, we describe the case of a 73-year-old female with coexisting pulmonary MALT lymphoma and carcinoid tumorlets of the right middle lobe. Retrospective series of 8 pulmonary MALT lymphomas are evaluated for neuroendocrine neoplasia by immunohistochemistry. No correlation between MALT lymphoma and neuroendocrine neoplasia was identified in this case series. While the concurrence of these distinctive neoplasms is most likely coincidental, the presence of a common risk factor, or one neoplasm as a risk factor for the other, deserves study of a larger group of pulmonary MALT lymphomas.

Correlation of neuroendocrine features with prognosis of non-small cell lung cancer

The improvement in histological diagnostic tools, including neuroendocrine markers by immunohistochemistry (IHC), has led to increased recognition of non-small cell lung cancer (NSCLC) with neuroendocrine (NE) feature. However, little is known regarding the prevalence and clinical implications of NE feature in patients with NSCLC. In this study, we performed IHC in a tissue microarray containing 451 Chinese NSCLC cases, and analyzed correlation of the expression of neuroendocrine marker with pathological and clinical features of NSCLC. The result showed that NE feature in NSCLC was detectable in almost 30% of studied patients, and tumors with NE feature were significantly correlated with pathological classification, clinical stages and cell differentiation of NSCLC. Our data also revealed that NE feature indicated worse overall survival and disease free survival. Compared with mutant p53, NE markers showed more significance as for prognostic evaluation. Multi-factor COX analysis further suggested a potential clinical impact for NE feature as an independent indicator of poor prognosis for NSCLC patients.

Management and Follow-up of Patients with a Bronchial Neuroendocrine Tumor in the Last Twenty Years in Ireland: Expected Inconsistencies and Unexpected Discoveries

Bronchial neuroendocrine tumors (NET) are classified into well-differentiated typical carcinoids (TC), atypical carcinoids (AC), large cell neuroendocrine carcinomas (LCNEC), and small cell lung carcinomas (SCLC). We retrospectively reviewed and analyzed the diagnostic and therapeutic aspects, follow-up data, and outcomes of all patients diagnosed with a bronchial NET from 1995 to 2015 at our institution. Patients with LCNEC or SCLC were excluded due to the biological and clinical differences from the other bronchial NET. The clinical, laboratory, imaging, treatment, and follow-up data were collected and analyzed keeping in mind the recently published international recommendations. Forty-six patients were included in the study. Of these, 37 had a TC and 5 an AC. In 4 patients, the histological characterization was inadequate. Forty-four patients underwent surgery. Four patients developed metastatic disease. Interestingly, 14 patients had one or more other tumors diagnosed at some stage and 3 of them had three different tumors. A total of 7 patients died. The analysis of the laboratory and pathology assessment identified some inconsistencies when compared to the international recommendations. Although the treatment of bronchial NET at our institution was consistent with the successively published recommendations, it appears that the diagnostic process and the follow-up surveillance were not. We think that a systematic multidisciplinary approach might improve bronchial NET patient care. A relatively high rate of occurrence of a second, or also a third, non-NET tumor was observed, though the statistical value of such observation could not be exhaustively elucidated in this numerically limited patient population. In our opinion, the observed high rate of second malignancies in this patient cohort highlights the necessity of optimizing the follow-up of the bronchial NET patients, also considering the very good survival rate achieved with regard to the bronchial NET.

Molecular challenges of neuroendocrine tumors

Neuroendocrine tumors (NETs) are a very heterogeneous group that are thought to originate from the cells of the endocrine and nervous systems. These tumors develop in a number of organs, predominantly in the gastrointestinal and pulmonary systems. Clinical detection and diagnosis are reliable at the late stages when metastatic spread has occurred. However, traditional conventional therapies such as radiation and chemotherapy are not effective. In the majority of cases even surgical resection at that stage is unlikely to produce promising reusults. NETs present a serious clinical challenge, as the survival rates remain low, and as these rare tumors are very difficult to study, novel approaches and therapies are required. This review will highlight the important points of accumulated knowledge covering the molecular aspects of the role of neuroendocrine cells, hormonal peptides, the reasons for ectopic hormone production in NET, neuropeptides and epigenetic regulation as well as the other challenging questions that require further understanding.

Nothing But NET: A Review of Neuroendocrine Tumors and Carcinomas

This review covers the diverse topic of neuroendocrine neoplasms (NENs), a relatively rare and heterogeneous tumor type, comprising ~2% of all malignancies, with a prevalence of <200,000 in the United States, which makes it an orphan disease (Basu et al., 2010).1 For functional purposes, NENs are divided into two groups on the basis of clinical behavior, histology, and proliferation rate: well differentiated (low grade to intermediate grade) neuroendocrine tumors and poorly differentiated (high grade) neuroendocrine carcinoma (Bosman et al., 2010)2; this histological categorization/dichotomization is highly clinically relevant with respect to impact on treatment and prognosis even though it is not absolute since a subset of tumors with a low-grade appearance behaves similarly to high-grade lesions. Given the relative dearth of evidenced-based literature about this orphan disease as a whole (Modlin et al., 2008),3 since the focus of most articles is on particular anatomic subtypes of NENs (i.e., gastroenteropancreatic or pulmonary), the purpose of this review is to summarize the presentation, pathophysiology, staging, current standard of care treatments, and active areas of current research.