High-grade Neuroendocrine Carcinoma of the Lung With Carcinoid Morphology: A Study of 12 Cases

Clinicopathological Profiling of Lung Carcinoids with a Ki67 Index > 20

The clinicopathological features of lung neuroendocrine neoplasms (NEN) with a high proliferative index at the border area between atypical carcinoid and neuroendocrine carcinoma have not been investigated so far. The aim of this study was, therefore, to search for lung NENs which are well differentiated but show Ki67 values that overlap with those of poorly differentiated (PD)-NENs. Resected lung NENs from 244 Japanese patients were reviewed, and Ki67 indices were assessed in all tumors. The data were then correlated to clinicopathological parameters and patient outcome. Among 59 (24%) well-differentiated (WD)-NENs and 185 (76%) lung PD-NENs, 7 were defined as WD-NENs with Ki67 indices > 20%. The Ki67 indices of these tumors (mean 29%, range 24-36) were significantly lower than those of PD-NENs (mean 74%, range 34-99). All WD-NENs with Ki67 > 20% lacked abnormal p53 and loss of retinoblastoma 1 (Rb1) expression. In contrast, many PD-NENs expressed p53 (48%) and showed loss of Rb1 (86%). The 2- and 5-year disease-free survival rates in WD-NEN patients with Ki67 > 20% were lower than those of WD-NEN patients with Ki67 ≤20% (p < 0.01 for disease-free and overall survival). No statistical differences were detected between outcome of WD-NEN patients with Ki67 > 20% and those of PD-NEN. It is concluded that WD-NEN patients with Ki67 > 20% share the morphological and immunohistochemical features of WD-NEN patients with Ki67 ≤20%, but they have a worse prognosis, suggesting that this tumor group requires particular attention in future classifications and probably new therapeutic regimes.

A common classification framework for neuroendocrine neoplasms: an International Agency for Research on Cancer (IARC) and World Health Organization (WHO) expert consensus proposal

The classification of neuroendocrine neoplasms (NENs) differs between organ systems and currently causes considerable confusion. A uniform classification framework for NENs at any anatomical location may reduce inconsistencies and contradictions among the various systems currently in use. The classification suggested here is intended to allow pathologists and clinicians to manage their patients with NENs consistently, while acknowledging organ-specific differences in classification criteria, tumor biology, and prognostic factors. The classification suggested is based on a consensus conference held at the International Agency for Research on Cancer (IARC) in November 2017 and subsequent discussion with additional experts. The key feature of the new classification is a distinction between differentiated neuroendocrine tumors (NETs), also designated carcinoid tumors in some systems, and poorly differentiated NECs, as they both share common expression of neuroendocrine markers. This dichotomous morphological subdivision into NETs and NECs is supported by genetic evidence at specific anatomic sites as well as clinical, epidemiologic, histologic, and prognostic differences. In many organ systems, NETs are graded as G1, G2, or G3 based on mitotic count and/or Ki-67 labeling index, and/or the presence of necrosis; NECs are considered high grade by definition. We believe this conceptual approach can form the basis for the next generation of NEN classifications and will allow more consistent taxonomy to understand how neoplasms from different organ systems inter-relate clinically and genetically.

Histomorphometric evaluation of the Ki-67 proliferation rate and CD34 microvascular and D2-40 lymphovascular densities drives the pulmonary typical carcinoid outcome

Ki-67 has shown promise as a prognostic factor in pulmonary carcinoids. In this study, we sought to validate the importance of Ki-67 and study the relationships between Ki-67 and other stromal biomarkers of vascular density. We examined Ki-67, CD34, and D2-40 in tumor tissues from 128 patients with surgically excised typical carcinoid of the lung. We used immunohistochemistry and morphometry to evaluate the amount of tumor staining for cellular proliferation (Ki-67), microvascular density (CD34-MVD), and D2-40 lymphovascular density. The main outcome was overall survival, considered as life expectancy until death from metastasis. Specimens from patients with central tumors showed high CD34-MVD (P = .01), which was also significantly associated with a compromised surgical margin, lymph node metastasis, and clinical stage Ib. Equally significant was high D2-40 lymphovascular density in central specimens with a compromised surgical margin and lymph node metastasis. A high Ki-67 proliferation rate was significantly associated with tumors from patients with clinical stage IIb, IIIa, and IV disease. Multivariate Cox model analysis demonstrated that tumor location and stage, surgical margin, tumor size, and N stage were significantly related to survival time (P < .05). Quantitative staining of the tumor for Ki-67 and CD34-MVD served as prognostic factors (P < .05), which were more relevant than the surgical and pathological stage. Ki-67 greater than 5% and CD34-MVD greater than 7% staining comprise a subset of patients with higher death hazard; this outcome may harbor evidence for further prospective studies of target therapy after surgical resection.

Updates on Selected Topics in Lung Cancers: Air Space Invasion in Adenocarcinoma and Ki-67 Staining in Carcinoid Tumors

Context.—

Air space invasion or aerogenous spread of lung adenocarcinoma is a relatively new concept and has been implicated as a potential prognostic factor as well as has been added as an exclusion point in the diagnosis of minimally invasive adenocarcinoma. Potential role for Ki-67 immunostaining as a diagnostic and prognostic marker in pulmonary carcinoid tumors has been suggested in the literature, given the significant interobserver variability and the difficulty in predicting their clinical behavior.

Objective.—

To review the concept of air space invasion in lung adenocarcinoma and the current controversies regarding the role of Ki-67 immunostaining on pulmonary carcinoid tumors

Data Sources.—

PubMed search of English literature.

Conclusions.—

Pathologists need to recognize air space invasion with a critical evaluation to differentiate it from artifacts that are commonly seen in sections. Currently, Ki-67 immunostaining is not recommended for routine use in the diagnosis of pulmonary carcinoid tumors or for predicting their prognosis, except for the differential diagnosis from small cell carcinomas or large cell neuroendocrine carcinomas in small biopsy specimens with crush artifacts.

New insights into hypoxia-related mechanisms involved in different microvascular patterns of bronchopulmonary carcinoids and poorly differentiated neuroendocrine carcinomas. Role of ribonuclease T2 (RNASET2) and HIF-1α

Ribonuclease T2 (RNASET2) is a pleiotropic and polyfunctional protein, which exerts several different activities in neoplastic cells since the early steps of tumor development. Besides having an antitumorigenic activity, RNASET2 inhibits both bFGF-induced and VEGF-induced angiogenesis and has a role as a stress-response, alarmin-like, protein. In this study, we investigated RNASET2 expression in well-differentiated and poorly differentiated neuroendocrine neoplasms of the lung (Lu-NENs), which are known to show clear-cut differences in morphology, biology and clinical behavior. In addition, we explored possible relationships between RNASET2 expression and a series of immunohistochemical markers related to hypoxic stress, apoptosis, proliferation and angiogenesis. Our results showed a significantly higher expression of RNASET2, HIF-1α, and its target CA IX in poorly differentiated than in well-differentiated Lu-NENs, the former also showing higher proliferation and apoptotic rates, as well as a lower microvessel density (MVD) than the latter. Moreover, we were able to demonstrate in vitro an overexpression of RNASET2 in consequence of the activation of HIF-1α. In conclusion, we suggest that in poorly differentiated Lu-NENs, RNASET2 expression may be induced by HIF-1α, behaving as an alarmin-like molecule. In this aggressive group of cancers, which have highly deregulated proliferation pathways, RNASET2 fails to exert the growth-inhibiting effects described in other types of neoplasms. Its increased expression, however, may contribute to the typical phenotypic alterations seen in poorly differentiated Lu-NENs, such as the high apoptotic rate and the extensive necrosis, and may also enhance the low MVD observed in these neoplasms.

Aggressive neuroendocrine tumor of the ovary with multiple metastases treated with everolimus: A case report

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Neuroendocrine tumors (NETs) frequently occur in the lungs or the gastrointestinal tract; they are uncommon in the ovary.

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The mammalian target of rapamycin (mTOR) pathway has been reported as a treatment for advanced NETs.

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We describe a patient with an aggressive primary ovarian NET, successfully treated with everolimus (an mTOR inhibitor).

Pulmonary large cell neuroendocrine carcinoma with adenocarcinoma-like features: napsin A expression and genomic alterations

Pulmonary large cell neuroendocrine carcinoma (LCNEC) is a highly aggressive malignancy, which was recently found to comprise three major genomic subsets: small cell carcinoma-like, non-small cell carcinoma (predominantly adenocarcinoma)-like, and carcinoid-like. To further characterize adenocarcinoma-like subset, here we analyzed the expression of exocrine marker napsin A, along with TTF-1, in a large series of LCNECs (n=112), and performed detailed clinicopathologic and genomic analysis of napsin A-positive cases. For comparison, we analyzed napsin A expression in other lung neuroendocrine neoplasms (177 carcinoids, 37 small cell carcinomas) and 60 lung adenocarcinomas. We found that napsin A was expressed in 15% of LCNEC (17/112), whereas all carcinoids and small cell carcinomas were consistently negative. Napsin A reactivity in LCNEC was focal in 12/17 cases, and weak or moderate in intensity in all cases, which was significantly lower in the extent and intensity than seen in adenocarcinomas (P<0.0001). The combination of TTF-1-diffuse/napsin A-negative or focal was typical of LCNEC but was rare in adenocarcinoma, and could thus serve as a helpful diagnostic clue. The diagnosis of napsin A-positive LCNECs was confirmed by classic morphology, diffuse labeling for at least one neuroendocrine marker, most consistently synaptophysin, and the lack of distinct adenocarcinoma component. Genomic analysis of 14 napsin A-positive LCNECs revealed the presence of mutations typical of lung adenocarcinoma (KRAS and/or STK11) in 11 cases. In conclusion, LCNECs are unique among lung neuroendocrine neoplasms in that some of these tumors exhibit low-level expression of exocrine marker napsin A, and harbor genomic alterations typical of adenocarcinoma. Despite the apparent close biological relationship, designation of adeno-like LCNEC as a separate entity from adenocarcinoma is supported by their distinctive morphology, typically diffuse expression of neuroendocrine marker(s) and aggressive behavior. Further studies are warranted to assess the clinical utility and optimal method of identifying adenocarcinoma-like and other subsets of LCNEC in routine practice.

Update on large cell neuroendocrine carcinoma

High-grade neuroendocrine carcinomas of the lung are classified into two categories: large cell neuroendocrine carcinoma (LCNEC) and small cell lung carcinoma (SCLC). While typical cases of LCNEC are morphologically distinct from SCLC, the differentiation between LCNEC and SCLC can be challenging in some cases. In fact, there are borderline high-grade neuroendocrine carcinomas that morphologically fall between LCNEC and SCLC. Growing evidence suggests that LCNEC is a histologically and biologically heterogeneous group of tumors. Molecular profiling with next-generation sequencing (NGS) has revealed a few biologically distinct subsets of LCNEC. Of those, the SCLC-like subset is characterized by concurrent inactivating mutations in TP53 and loss of RB1 that are typically seen in SCLC, whereas the non-small cell lung cancer (NSCLC)-like subset frequently harbors molecular alterations that are usually seen in NSCLC. Furthermore, the SCLC-like subset exhibits morphologic features of SCLC, and NSCLC-like morphology predominates in the NSCLC-like subset, although there was a substantial overlap in morphologic features between these subsets. As for the treatment of LCNEC, surgery is advocated for early stage tumors, but surgery alone does not appear to be sufficient and adjuvant chemotherapy, consisting of platinum/etoposide, likely prevents recurrence in patients with completely resected LCNEC. For advanced disease, there have been conflicting reports as to whether LCNEC responds to chemotherapeutic regimens in the similar manner to SCLC rather than NSCLC, and the heterogeneous biology of LCNEC may contribute in part to the discrepant results. A further understanding of the biology of LCNEC will lead to novel approaches to clinical managements of patients with LCNEC.

Classification of pulmonary neuroendocrine tumors: new insights

Neuroendocrine tumors of the lung (Lu-NETs) embrace a heterogeneous family of neoplasms classified into four histological variants, namely typical carcinoid (TC), atypical carcinoid (AC), large cell neuroendocrine carcinoma (LCNEC) and small cell lung carcinoma (SCLC). Defining criteria on resection specimens include mitotic count in 2 mm2 and the presence or absence of necrosis, alongside a constellation of cytological and histological traits including cell size and shape, nuclear features and overall architecture. Clinically, TC are low-grade malignant tumors, AC intermediate-grade malignant tumors and SCLC/LCNEC high-grade malignant full-blown carcinomas with no significant differences in survival between them. Homologous tumors arise in the thymus that occasionally have some difficulties in differentiating from the lung counterparts when presented with large unresectable or metastatic lesions. Immunohistochemistry (IHC) helps refine NE diagnosis at various anatomical sites, particularly on small-sized tissue material, in which only TC and small cell carcinoma categories can be recognized easily on hematoxylin & eosin stain, while AC and LCNEC can only be suggested on such material. The Ki-67 labeling index effectively separates carcinoids from small cell carcinoma and may prove useful for the clinical management of a metastatic disease to help the therapeutic decision-making process. Although carcinoids and high-grade neuroendocrine carcinomas in the lung and elsewhere make up separate tumor categories on molecular grounds, emerging data supports the concept of secondary high-grade NETs arising in the preexisting carcinoids, whose clinical and biological relevance will have to be placed into the proper context for the optimal management of these patients. In this review, we will discuss the selected, recent literature with a focus on current issues regarding Lu-NET nosology, i.e., classification, derivation and tumor evolution.

Distinctive pathological and clinical features of lung carcinoids with high proliferation index

Typical (TCs) and atypical carcinoids (ACs) are defined based on morphological criteria, and no grading system is currently accepted to further stratify these entities. The 2015 WHO classification restricts the Ki-67 role to biopsy or cytology samples, rather than for prognostic prediction. We aimed to investigate whether values and patterns of Ki-67 alone would allow for a clinically meaningful stratification of lung carcinoids, regardless of histological typing. Ki-67 proliferation index and pattern (homogeneous versus heterogeneous expression) were assessed in a cohort of 171 TCs and 68 ACs. Cases were subdivided into three Ki-67 ranges (<4/4–9/≥10%). Correlations with clinicopathological data, univariate and multivariate survival analyses were performed. The majority of cases (61.5%) belonged to the <4% Ki-67 range; 25.1 and 13.4% had a proliferation index of 4–9% and ≥10%, respectively. The <4% Ki-67 subgroup was significantly enriched for TCs (83%, p < 0.0001); ACs were more frequent in the subgroup showing Ki-67 ≥ 10% (75%, p < 0.0001). A heterogeneous Ki-67 pattern was preferentially seen in carcinoids with a Ki-67 ≥10% (38%, p < 0.02). Mean Ki-67 values ≥4 and ≥10% identified categories of poor prognosis both in terms of disease-free and overall survival (p = 0.003 and <0.0001). At multivariate analysis, the two thresholds did not retain statistical significance; however, a Ki-67 ≥ 10% identified a subgroup of dismal prognosis even within ACs (p = 0.03) at univariate analysis. Here, we describe a subgroup of lung carcinoids showing brisk proliferation activity within the necrosis and/or mitotic count-based categories. These patients were associated with specific clinicopathological characteristics, to some extent regardless of histological subtyping.