Typical and atypical bronchopulmonary carcinoid tumors: a clinicopathologic and KI-67-labeling study

Prognostic Immunohistochemistry for Ki-67 and OTP on Small Biopsies of Pulmonary Carcinoid Tumors: Ki-67 Index Predicts Progression-free Survival and Atypical Histology

Prognostic stratification of pulmonary carcinoids into "typical" and "atypical" categories requires examination of large tissue volume. However, there is a need for tools that provide similar prognostic information on small biopsy samples. Ki-67 and OTP immunohistochemistry have shown promising prognostic value in studies of resected pulmonary carcinoids, but prognostic value when using biopsy/cytology specimens is unclear. Ki-67 immunohistochemistry was performed on small biopsy/cytology specimens from pulmonary carcinoid tumors (n=139), and labeling index was scored via automated image analysis of at least 500 cells. OTP immunohistochemistry was performed on 70 cases with sufficient tissue and scored as positive or negative (<20% tumor nuclei staining). Higher Ki-67 index was associated with worse disease-specific progression-free survival (ds-PFS), with 3% and 4% thresholds having similarly strong associations with ds-PFS ( P <0.001, hazard ratio ≥11). Three-year ds-PFS was 98% for patients with Ki-67 <3% and 89% for patients with Ki-67≥3% ( P =0.0006). The optimal Ki-67 threshold for prediction of typical versus atypical carcinoid histology on subsequent resection was 3.21 (AUC 0.68). Negative OTP staining approached significance with atypical carcinoid histology ( P =0.06) but not with ds-PFS ( P =0.24, hazard ratio=3.45), although sample size was limited. We propose that Ki-67 immunohistochemistry may contribute to risk stratification for carcinoid tumor patients based on small biopsy samples. Identification of a 3% hot-spot Ki-67 threshold as optimal for prediction of ds-PFS is notable as a 3% Ki-67 threshold is currently used for gastrointestinal neuroendocrine tumor stratification, allowing consideration of a unified classification system across organ systems.

Improvement of Lung NET Management through Standardized Care-A Swiss Nationwide Observational Study

Typical (TC) and atypical carcinoids (AC) are the most common neuroendocrine tumors (NETs) of the lung. Because these tumors are rare, their management varies widely among Swiss centers. Our aim was to compare the management of Swiss patients before and after the publication of the expert consensus of the European Neuroendocrine Tumor Society (ENETS) in 2015. We used data from the Swiss NET registry from 2009 to 2021 with patients with TC and AC. Survival analysis was performed using the Kaplan-Meier method and log-rank test. Overall, 238 patients were included, 76% (180) thereof with TC and 24% (58) with AC, including 155 patients before and 83 patients after 2016. An increase in the use of functional imaging was observed, 16% (25) before and 35% (29) after 2016, p < 0.001. The presence of SST_2A-receptors was determined more often: 32% (49 times) before 2016 and 47% (39 times) after, p = 0.019. Concerning therapy, higher removal of lymph nodes after 2016 was observed, 54% (83) before versus 78% (65) after, p < 0.001. Median overall survival for patients with AC was significantly shorter, with 89 months compared to 157 months for patients with TC, p < 0.001. While the implementation of a more standardized approach was observed over the years, there is still room for amelioration in the management of TC and AC in Switzerland.

SATB2 Is Expressed in a Subset of Pulmonary and Thymic Neuroendocrine Tumors

OBJECTIVES

To evaluate SATB2 expression and prognostic implications in a large cohort of thoracic neuroendocrine tumors.

METHODS

Surgical pathology files (1995-2017) and an institutional thymic epithelial tumor database (2010-2020) were searched for resected neuroendocrine tumors. Cases were stained with SATB2 (clone EP281). Percent SATB2-positive tumor cells and expression intensity were scored.

RESULTS

In the lung, SATB2 was expressed in 5% or more of tumor cells in 29 (74.4%) of 39 small cell carcinomas and 9 (22.5%) of 40 atypical and 26 (40.6%) of 64 typical carcinoid tumors. SATB2 percent tumor cell expression and intensity were higher in small cell carcinomas than in carcinoid tumors (both P < .001, respectively). After adjusting for tumor subtype, SATB2 expression did not correlate with outcome. In the thymus, four (100%) of four atypical carcinoid tumors and one large cell neuroendocrine carcinoma but no small cell carcinoma (n = 2) expressed SATB2 in 5% or more of tumor cells.

CONCLUSIONS

SATB2 (clone EP281) is expressed in a large subset of pulmonary and thymic neuroendocrine tumors and therefore does not appear to be a useful marker to identify the origin of neuroendocrine tumors. Validation studies are needed, specifically including thymic neuroendocrine tumors, as the expression pattern might be different in those tumors.

Update on Histological Reporting Changes in Neuroendocrine Neoplasms

PURPOSE OF REVIEW

Classification and nomenclature of neuroendocrine neoplasms (NEN) have frequently changed over the last years. These changes reflect both increasing knowledge and international standardisation.

RECENT FINDINGS

The most recent changes in the Gastro-Entero-Pancreatic system induced the concept of well-differentiated NET with high proliferation rate (NET G3), explaining partially the heterogeneity of G3 NEN. Even if the nomenclature in pulmonary NEN is still different, the terms 'carcinoid' and 'atypical carcinoid' are widely overlapping with NET G1 and NET G2. Molecular data shows an additional heterogeneity both in well-differentiated NET and poorly differentiated NEC. However, no studies are available demonstrating clinical usefulness yet. The heterogeneity of NEN regarding the organ of origin, differentiation and molecular subtypes make development of personalised therapy a challenge needing more international and interdisciplinary collaborations and clinical trials allowing stratification according to biological subgroups.

Prognostic significance of histopathological factors in survival and recurrence of atypical carcinoid tumours

OBJECTIVES

Atypical carcinoids are neuroendocrine neoplasms of intermediate degree and low frequency. The aim of this study is to analyse their clinical characteristics and the importance of different histopathological factors in their prognosis.

METHODS

Multicentre cooperative group EMETNE prospectively reviewed 153 patients operated on between 1998 and 2016 with diagnosis of atypical carcinoids. Clinical variables and histopathological features were assessed.

RESULTS

Mean age was 54.36 years, similar for both genders. Concerning pathological study, mean tumour size was 31.7 mm. Rosettes were presented in 17% of the cases and tumoural necrosis in 23.3%. The cell proliferation factor Ki-67 index was 10.7%. The 2- and 5-year overall survival rates were 95.8% and 88.9%, respectively. In the univariate study, statistically significant differences in survival were found for each of the categories of T, N and M factors. Mitotic index and quantification of expression of Ki-67 showed influence in overall survival, although without statistical significance. In the multivariate analysis, factors N, M and mitotic index behaved as independent prognostic factors related to survival. Median disease-free interval in the series was 163.35 months. In cases with loco-regional recurrence, 53% had positive hiliar or mediastinal nodal involvement at the time of the surgery. In the univariate analysis, we observed statistically significant differences in disease-free interval in patients with nodal involvement (P = 0.024) and non-anatomical resections (P = 0.04). Histological characteristics showed no statistically significant differences in disease-free interval.

CONCLUSIONS

Lymph node involvement, the development of distant metastasis and mitotic index, more than Ki-67 determination, were shown as independent prognostic factors related to survival of these patients.

Neuroendocrine tumors of the lung: clinicopathological and molecular features

In 1970, neuroendocrine tumors of the lung were classified into three categories: typical carcinoid (TC), atypical carcinoid (AC), and small cell lung carcinoma (SCLC). The third edition of the World Health Organization (WHO) classification in 1999 defined large cell neuroendocrine carcinoma (LCNEC) as a variant of large cell carcinomas, whereas the fourth edition of the WHO classification redefined LCNEC as a neuroendocrine tumor. Currently, neuroendocrine tumors of the lung are classified into four main categories: TC, AC, LCNEC, and SCLC. Although the treatments for TC, AC, and SCLC have not changed remarkably, the treatment strategy for LCNEC is not yet established because of its reclassification from a variant of "large cell carcinoma" to a new category of "neuroendocrine tumor". In this review article, we discuss the pathological findings, biological behavior, and treatment of neuroendocrine tumors of the lung.

Ki-67 Labeling Index in Pulmonary Carcinoid Tumors: Comparison Between Small Biopsy and Resection Using Tumor Tracing and Hot Spot Methods

CONTEXT.—

Pulmonary carcinoids are classified as typical or atypical by assessing necrosis and mitoses, which usually cannot be adequately assessed on small biopsies. Ki-67 is not currently used to grade pulmonary carcinoids, but it may be helpful to determine preliminary grade in biopsies. However, the rate at which Ki-67 could underestimate or overestimate grade on small biopsies has not been well studied.

OBJECTIVE.—

To compare Ki-67 labeling obtained on small biopsies to subsequent resection.

DESIGN.—

Ki-67 was performed on paired biopsy and resection specimens from 55 patients. Slides were scanned using Aperio ScanScope. Labeling index was determined using automated hot spot and tumor tracing methods.

RESULTS.—

The study included 41 typical and 14 atypical carcinoids. Atypical carcinoids were larger and had more distant metastases. Death from disease occurred in 3 patients (all had atypical carcinoids). Median hot spot Ki-67 labeling index was greater in resection compared with biopsy by 0.7% (P = .02). Median tumor tracing Ki-67 was lower in resection compared with biopsy by 0.5% (P < .001). Receiver-operating characteristic analysis showed similar hot spot Ki-67 cutoffs to predict atypical histology (3.5% for biopsy, 3.6% for resection; area under the curve [AUC], 0.75 and 0.74, respectively). Different optimal cutoffs were needed for tracing method based on biopsy (2.1%; AUC, 0.75) compared with resection (1.0%; AUC, 0.67).

CONCLUSIONS.—

Hot spot Ki-67 tends to underestimate grade on small biopsies, whereas grade is overestimated by tumor tracing. Hot spot Ki-67 cutoff of 3.5% predicted atypical histology for both biopsy and resection. Different biopsy and resection cutoffs were necessary for tumor tracing, which would make clinical implementation more difficult.

Loss of ATRX expression predicts worse prognosis in pulmonary carcinoid tumors

Loss of alpha thalassemia/mental retardation syndrome X-linked (ATRX), a chromatin regulator, is associated with worse prognosis in pancreatic neuroendocrine tumors. We investigated ATRX expression in pulmonary carcinoid tumors (PCT) and its diagnostic and prognostic role in these patients. Resected PCTs (1997-2017) were reviewed. Tumors were staged according to 8th UICC/AJCC system. ATRX nuclear expression was recorded independently by 2 reviewers. A cutoff of ≤5% of nuclear ATRX expression was statistically established as loss of expression. One-hundred-fifteen patients (72 women [63%]; median age of 60.5 years [interquartile range, 50.8-71.5]) harbored 69 (60%) typical and 46 (40%) atypical PCTs. Median tumor size was 2.3 cm (interquartile range, 1.6-3.8 cm). Loss of ATRX expression was associated with atypical PCTs (OR 7.4 [95% CI, 2.6-23, P < .001]), when adjusted for lymphovascular invasion and perineural invasion. ATRX expression predicted atypical PCT with sensitivity of 37% (95% CI, 24%-52%), specificity of 92% (95% CI, 86%-98%), AUC of 0.62 (95% CI, 0.52-0.72). Loss of ATRX expression was associated with shorter disease-specific survival (HR = 11, 95% CI, 1.8-68, P = .01), after adjusting for lymphovascular invasion and presence of metastatic disease at time of diagnosis. Interobserver agreement on ATRX expression by two reviewers was substantial (κ = 0.72 [95% CI, 0.60-0.80]). ATRX expression is more commonly lost in atypical than in typical PCT, and is associated with more aggressive tumor characteristics and shorter disease-specific survival.

Unmet Medical Needs in Pulmonary Neuroendocrine (Carcinoid) Neoplasms

Pulmonary carcinoids (PCs) display the common features of all well-differentiated neuroendocrine neoplasms (NEN) and are classified as low- and intermediate-grade malignant tumours (i.e., typical and atypical carcinoid, respectively). There is a paucity of randomised studies dedicated to advanced PCs and management principles are drawn from the larger gastroenteropancreatic NEN experience. There is growing evidence that NEN anatomic subgroups have different biology and different responses to treatment and, therefore, should be investigated as separate entities in clinical trials. In this review, we discuss the existing evidence and limitations of tumour classification, diagnostics and staging, prognostication, and treatment in the setting of PC, with focus on unmet medical needs and directions for the future.

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.

The use of Ki-67 labeling index to grade pulmonary well-differentiated neuroendocrine neoplasms: current best evidence

Although Ki-67 labeling index (Ki-67%) is not a diagnostic or grading criterion in the World Health Organization classification of pulmonary carcinoid tumor, oncologists often request this test. A survey was administered at a North American Society for Neuroendocrine Tumors meeting to understand how Ki-67% is used in oncologic practices. A systematic literature review was performed to gather best evidence regarding the use of Ki-67%. Consecutive pulmonary carcinoids were stratified into pulmonary typical carcinoids with Ki-67% <5% (group A, n = 187), typical carcinoids with Ki-67% ≥5% (group B, n = 38) and atypical carcinoids irrespective of Ki-67% (group C, n = 31). Overall survival, progression-free survival, recurrence proportions and time to recurrence were compared, by group, using the log-rank test, chi-square statistics and ANOVA, respectively. Our survey confirmed that Ki-67% is frequently used by specialists caring for these patients. Ki-67% of 1-7% significantly correlated with overall survival in the literature but we found no information about Ki-67% cut-off values that would accurately distinguish pulmonary typical from atypical carcinoids or estimate the prognosis of patients stratified by World Health Organization diagnosis and Ki-67% cut-off. Overall survival was significantly different in our 3 patient groups (p < 0.001), with survival probabilities decreasing from groups A to C. Progression-free survival was significantly longer in group A than B (p < 0.007). Our results support the concept that by combining World Health Organization diagnosis and Ki-67%, pulmonary carcinoids can be stratified into 3 grades: G1 (typical carcinoids with Ki-67% <5), G2 (typical carcinoids with Ki-67% ≥5%) and G3 (atypical carcinoids) with different prognoses.

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.

Solitary pulmonary nodule evaluation in regions endemic for infectious diseases: Do regional variations impact the effectiveness of fluorodeoxyglucose positron emission tomography/computed tomography

BACKGROUND

Fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) has become a preferred imaging modality for the evaluation of solitary pulmonary nodule (SPN), particularly in the developed world. Since FDG can concentrate in infective/inflammatory lesions, the diagnostic utility of FDG-PET can be questioned, particularly in regions endemic for infectious decisions.

AIM

To evaluate the accuracy of FDG-PET/CT in evaluation of SPNs in a population endemic for infectious disease and to assess if regional variations have an impact on its effectiveness.

MATERIALS AND METHODS

All patients who underwent an FDG/PET-CT with a clinico-radiological diagnosis of SPN categorized as indeterminate were included. Based on a maximum standardized uptake values (SUVmax) cut-off of 2.5, lesions were classified as benign (<2.5) or malignant (>2.5) and compared with gold standard histopathology. The diagnostic accuracy of PET-CT to detect malignancy was calculated. On the basis of final histopathology, lesions were grouped as (a) malignant nodules (b) infective/granulomatous nodules with a specific diagnosis and (c) nonspecific inflammatory nodules. The SUVmaxbetween these groups was compared using nonparametric statistical tests.

RESULTS

A total of 191 patients (129 males, 62 females) with a median age of 64 years (range: 36-83) were included. Totally, 144 nodules (75.3%) were malignant and 47 were benign (24.7%). Adenocarcinoma (n = 84) was the most common malignancy. Tuberculosis (n = 16) and nonspecific infections (n = 24) were the two most common benign pathologies. There was a significant overlap in the metabolic uptake of malignant (median SUVmax-11.2, range: 3.3-34.6) and tuberculous nodules (median SUVmax-10.3, range: 2.7-22.5) with no statistically difference between their SUVmaxvalues (P = 0.43). The false-positive rate was 65.2% and the false-negative rate was 5.5%. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of FDG-PET/CT for detecting malignancy were 94.4%, 34.7%, 81.9%, 66.6%, and 79.5%, respectively.

CONCLUSIONS

Though FDG-PET scans show a very high sensitivity for malignant nodules, it has a high false-positive rate and reduced specificity when characterizing SPNs in an infectious endemic region. Physicians must be aware of this limitation in the workup of lung nodules, and regional variations must be considered before further management decisions are taken.

Lung neuroendocrine tumors: pathological characteristics

Lung neuroendocrine tumors (NETs) are a heterogeneous family of neoplasms comprising four histologic types, namely typical and atypical carcinoid (TC and AC), large-cell neuroendocrine and small cell carcinoma (SCC). Classification criteria include the number of mitoses per 2 mm2, the occurrence and extent of necrosis, cytological and histological features and immunohistochemistry for neuroendocrine markers. The classification system and the diagnostic workflow of lung NETs are apparently easy to apply and well established. However, several unresolved issues still exist in classification and pathological characterization of these tumors, probably because inter-observer diagnostic reproducibility remains disappointing, likely due to inconsistency in recognizing necrosis, mitoses and cytological details, especially in small biopsy or cytological materials. Furthermore, the lack of strong prognostic and grading criteria leads to the incomplete interpretation of some rare intermediate entities that stand in between AC and large cell neuroendocrine carcinoma (LCNEC) categories.

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.

Ki-67 labeling index of neuroendocrine tumors of the lung has a high level of correspondence between biopsy samples and surgical specimens when strict counting guidelines are applied

Optimal histopathological analysis of biopsies from metastases of neuroendocrine tumor (NET) of the lung requires more than morphology only. Additional parameters such as Ki-67 labeling index are required for adequate diagnosis, but few studies have compared reproducibility of different counting protocols and modalities of reporting on biopsies of lung NET. We compared the results of four different manual counting techniques to establish Ki-67 LI. On 47 paired biopsies and surgical specimens from 22 typical carcinoids (TCs), 14 atypical carcinoids (ACs), six large cell neuroendocrine carcinomas (LCNECs), and five small cell carcinomas (SCCs) immunohistochemical staining of Ki-67 antigen was performed. We counted, in regions of highest nuclear staining (HSR), a full ×40-high-power field (diameter = 0.55 mm), 500 or 2000 cells, or 2 mm² surface area, including the HSR or the entire biopsy fragment(s). Mitoses and necrosis were evaluated in an area of 2 mm² or the entire biopsy fragment(s). Between the four counting methods, no differences in Ki-67 LI were observed. However, a Ki-67 LI higher than 5% was found in only four cases when in an HSR, 500 cells were counted (18%), five (23%) when in an HSR 2000 cells were counted, four (18%) when 2 mm² were counted, and one (5%) TC case when the entire biopsy was counted. A 20% cutoff distinguished TC and AC from LCNEC and SCC with 100% specificity and sensitivity, while mitoses and necrosis failed to a large extent. Ki-67 LI in biopsy samples was concordant with that in resection specimens when 2000 cells, 2 mm², or the entire biopsy fragment(s) were counted. Our results are important for clinical management of patients with metastases of a lung NET.

Limited additive value of the Ki-67 proliferative index on patient survival in World Health Organization-classified pulmonary carcinoids

AIMS

Currently pulmonary carcinoids are separated into typical and atypical based on mitotic count and presence of necrosis, according to the World Health Organization. At variance with gastroenteropancreatic neuroendocrine tumours, which are graded based on mitotic count and Ki-67 proliferative index, the use of Ki-67 for grading pulmonary carcinoids is still under debate.

METHODS AND RESULTS

In this study we evaluated the prognostic impact of Ki-67 assessment in a multicentre cohort of 201 carcinoids [147 typical carcinoids (TCs) and 54 atypical carcinoids (ACs)] using manual analysis (2000 cells counted) and digital image analysis (in-house Leica Qwin program; ≥4500 cells counted). The Ki-67 proliferative index was correlated with overall survival by means of univariate analysis and in comparison to clinical data by means of multivariable analysis. The Ki-67 index was significantly higher in ACs than in TCs for both counting methods (P ≤ 2.7e^-5 ). In addition, using cut-offs of 2.5% and 4% (manual counting) or 1% and 5% (digital analysis), the highest differences in overall survival were observed (P ≤ 0.0067). Nevertheless, histopathological classification into TCs and ACs showed an equally strong association with disease outcome, although Ki-67 had some additive value within TCs. Ki-67 index was not an independent predictor of survival in multivariable analysis.

CONCLUSIONS

Our study demonstrates that, although Ki-67 is a strong prognostic factor for pulmonary carcinoids, its usefulness in addition to histopathology in prediction of prognosis is limited. None the less, it may have additional value, especially in cases that are difficult to classify, in combination with histopathology and other molecular markers.

Evaluation of diagnostic and prognostic significance of Ki-67 index in pulmonary carcinoid tumours

BACKGROUND

Pulmonary carcinoid (PC) tumours are classified as either typical (TC) or atypical (AC) according to mitotic index (MI) and presence of necrosis. The aim of this study was to analyse the diagnostic and prognostic values of the Ki-67 index in PC.

METHODS/PATIENTS

Between January 2001 and March 2015, we evaluated 94 consecutive patients with a confirmed diagnosis of TC (n = 75) or AC (n = 19) at our institution. Diagnostic histology was centrally reviewed by a local expert neuroendocrine pathologist, with assessment of Ki-67, MI, and necrosis.

RESULTS

Median patient follow-up was 35 months. Eighty-four patients who underwent curative surgical resection were included in the survival analysis for identification of prognostic factors. Ki-67 index showed high diagnostic accuracy to predict histological subtype when assessed by receiver operator characteristic curves with an area under the curve of 0.923 (95% CI 0.852-0.995, p < 0.001). Multivariate analysis showed that MI, Ki-67 index, and the presence or absence of necrosis were independent prognostic factors for relapse-free survival. Combination of MI, Ki-67, and necrosis led to the classification of patients into four different prognostic groups (very low, low, intermediate, and high risks of relapse).

CONCLUSIONS

The current study proposes the incorporation of Ki-67 index in the prognostic classification of PC tumours. Due to the limited number of patients and length of follow-up, the current model needs validation by larger cohort studies. Nevertheless, our results suggest that Ki-67 index and MI have continuous effect on prognosis. Prognostic models incorporating multiple cutoffs of Ki-67 and MI might better predict outcome and inform clinical decisions.

The oncofetal protein IMP3: a useful marker to predict poor clinical outcome in neuroendocrine tumors of the lung

INTRODUCTION

We evaluated the expression of the oncofetal protein IMP3 in a series of neuroendocrine tumors of the lung, correlating our results with proliferating index Ki67 and with the expression of the two most studied stem cell markers in lung cancer, Nanog and Oct3/4.

METHODS

A total of 74 patients with a diagnosis of neuroendocrine tumor including 46 cases of typical carcinoid, nine cases of atypical carcinoids, 13 cases of large cell neuroendocrine carcinomas and six cases of small cell carcinomas were enrolled.

RESULTS

IMP3 was expressed in 50% of small cell carcinomas, 84% of large cell neuroendocrine carcinomas, 55% of atypical carcinoids and 10% of typical carcinoids. IMP3-positive cases showed significantly decreased overall and disease-free survival time compared with IMP3-negative cases. Nanog was expressed in 50% of small cell carcinomas, 31% of large cell neuroendocrine carcinomas, 33% of atypical carcinoids and 15% of typical carcinoids, and 68% of IMP3-positive tumors were also enriched for Nanog expression. Conversely, Oct3/4 expression could not be detected in all the analyzed series. When combining Ki67 and IMP3 expression we demonstrated that all the cases with a Ki67 index higher than 4% were also IMP3-positive, and their simultaneous expression was a poor prognostic factor.

CONCLUSIONS

IMP3 is a marker of poor outcome in lung neuroendocrine tumors; its correlation with Nanog expression suggest an implication of IMP3 in stem cell processes and its association with a Ki67 labeling index higher than 4% stratifies a subset of atypical carcinoids with a higher risk of recurrence and mortality.

Usefulness of Ki-67, Mitoses, and Tumor Size for Predicting Metastasis in Carcinoid Tumors of the Lung: A Study of 48 Cases at a Tertiary Care Centre in Canada

Background. Evaluation of Ki-67 index in lung carcinoid tumors (LCTs) has been of interest in order to identify high risk subsets. Our objectives are (1) to evaluate the usefulness of Ki-67 index, mitoses, and tumor size in predicting metastasis and (2) to compare the Manual Conventional Method (MCM) and the Computer Assisted Image Analysis Method (CIAM) for Ki-67 calculation. Methods. We studied 48 patients with LCTs from two academic centres in Canada. For Ki-67 calculation, digital images of 5000 cells were counted using an image processing software and 2000 cells by MCM. Mitoses/10 HPF was counted. Results. We had 37 typical carcinoids (TCs) and 11 atypical carcinoids (ACs). 7/48 patients developed metastasis. There was a positive relationship between metastasis and carcinoid type (P = 0.039) and metastasis and mitoses (≥2) (P = 0.017). Although not statistically significant, the mean Ki-67 index for ACs was higher than for TCs (0.95% versus 0.72%, CIAM, P = 0.299). Similarly, although not statistically significant, the mean Ki-67 index for metastatic group (MG) was higher than for nonmetastatic group (NMG) (1.01% versus 0.71% by CIAM, P = 0.281). However when Ki-67 index data was categorized at various levels, there is suggestion of a useful cutoff (≥0.50%) to predict metastasis (P = 0.106, CIAM). A significantly higher proportion of patients with mitosis ≥2 and Ki-67 index ≥0.50% had metastasis (P = 0.033) compared to other patients. Similarly patients with tumor size ≥3 cm and Ki-67 ≥0.50% had a greater percentage of metastases than others (P = 0.039). Although there was a strong correlation between two (MCM versus CIAM) counting methods (r = 0.929, P = 0.001), overall the calculated Ki-67 index was slightly higher by MCM (range 0 to 6.4, mean 1.5) compared to CIAM (range 0 to 2.9, mean 0.75). Conclusion. This study confirms that mitoses ≥2 is a powerful predictor of metastasis in LCTs. Although this is a small sample size, there is suggestion that analysis of Ki-67 index along with mitoses and tumor size may be a useful adjunct for predicting metastasis in LCTs.

What clinicians are asking pathologists when dealing with lung neuroendocrine neoplasms?

Lung neuroendocrine tumors (NET) are currently classified in resection specimens according to four histological categories, namely typical carcinoid (TC), atypical carcinoid (AC), large-cell neuroendocrine carcinoma (LCNEC) and small cell carcinoma (SCC). Diagnostic criteria have remained unchanged in the 2015 WHO classification, which has ratified the wide acceptance and popularity of such terminology in the pathologists׳ and clinicians׳ community. A unifying umbrella of NE morphology and differentiation has been recognized in lung NET, which has pushed to enter an unique box of invasive tumors along with diffuse idiopathic pulmonary NE cell hyperplasia (DIPNECH) as a pre-invasive lesion with a potential toward the development of carcinoids. However, uncertainties remain in the terminology of lung NET upon small samples, where Ki-67 antigen could play some role to avoid misdiagnosing carcinoids as high-grade NE tumors. Epidemiologic, clinical and genetic traits support a biological three-tier over a pathology four-tier model, according to which TC are low malignancy tumors, AC intermediate malignancy tumors and LCNEC/SCC high malignancy tumors with no significant differences in survival among them. Inconsistencies in diagnostic reproducibility, troubles in the therapy of AC and LCNEC, and limitations to histology within the same tumor category argue in favor of a global re-thinking of lung NET where a grading system could play a role. This review outlines three main key questions in the field of lung NET: (A) unbiased diagnoses, (B) the role of Ki-67 and tumor grading, and (C) management of predictive markers. Answers are still inconclusive, thus additional research is required to improve our understanding on lung NET.

Pulmonary neuroendocrine (carcinoid) tumors: European Neuroendocrine Tumor Society expert consensus and recommendations for best practice for typical and atypical pulmonary carcinoids

BACKGROUND

Pulmonary carcinoids (PCs) are rare tumors. As there is a paucity of randomized studies, this expert consensus document represents an initiative by the European Neuroendocrine Tumor Society to provide guidance on their management.

PATIENTS AND METHODS

Bibliographical searches were carried out in PubMed for the terms 'pulmonary neuroendocrine tumors', 'bronchial neuroendocrine tumors', 'bronchial carcinoid tumors', 'pulmonary carcinoid', 'pulmonary typical/atypical carcinoid', and 'pulmonary carcinoid and diagnosis/treatment/epidemiology/prognosis'. A systematic review of the relevant literature was carried out, followed by expert review.

RESULTS

PCs are well-differentiated neuroendocrine tumors and include low- and intermediate-grade malignant tumors, i.e. typical (TC) and atypical carcinoid (AC), respectively. Contrast CT scan is the diagnostic gold standard for PCs, but pathology examination is mandatory for their correct classification. Somatostatin receptor imaging may visualize nearly 80% of the primary tumors and is most sensitive for metastatic disease. Plasma chromogranin A can be increased in PCs. Surgery is the treatment of choice for PCs with the aim of removing the tumor and preserving as much lung tissue as possible. Resection of metastases should be considered whenever possible with curative intent. Somatostatin analogs are the first-line treatment of carcinoid syndrome and may be considered as first-line systemic antiproliferative treatment in unresectable PCs, particularly of low-grade TC and AC. Locoregional or radiotargeted therapies should be considered for metastatic disease. Systemic chemotherapy is used for progressive PCs, although cytotoxic regimens have demonstrated limited effects with etoposide and platinum combination the most commonly used, however, temozolomide has shown most clinical benefit.

CONCLUSIONS

PCs are complex tumors which require a multidisciplinary approach and long-term follow-up.

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.

Ki-67 antigen in lung neuroendocrine tumors: unraveling a role in clinical practice

Classification of lung neuroendocrine (NE) tumors is a step-wise process with four tumor categories being identified by morphology, namely typical carcinoid (TC), atypical carcinoid, large-cell NE carcinoma, and small-cell lung carcinoma (SCLC). Ki-67 antigen or protein (henceforth simply Ki-67) has been largely studied in these tumors, but the clinical implications are so far not clear. A well-defined role has regarded the diagnostic use in the separation of TC and AC from SCLC in nonsurgical specimens, with monoclonal antibody MIB-1 resulting in the most used reagent after antigen retrieval procedures. Uncertainties, however, have arisen in its assessment, usually expressed as Ki-67 labeling index, because of some variability in obtaining either value of the fraction. A diagnostic role is currently lacking, even though there are significant differences in most cases between TC and AC, less so between large-cell NE carcinoma and SCLC. In addition, the prognostic role of Ki-67 is debated, likely due to methodological and biological reasons. The last challenge would be to identify an effective lung-specific grading system based on Ki-67 labeling index. In this review article, five relevant issues to Ki-67 have been addressed by using a question-answer methodology, with relevant key points discussing major interpretation issues. The conclusion is that Ki-67 is a feasible and potentially meaningful marker in lung NE tumors, but more data are needed to determine its ideal function in this setting of tumors.

Automated quantification of Ki-67 proliferative index of excised neuroendocrine tumors of the lung

BACKGROUND

The histopathologic distinction between typical carcinoid (TC) and atypical carcinoid (AC) of the lung is based largely on mitotic index. Ki-67 may aid in separation of these tumors, as well as the distinction from large cell neuroendocrine carcinoma (LCNEC).

METHODS

We identified 55 surgically resected primary neuroendocrine lung tumors (39 TC, 7 AC, 9 LCNEC) based on mitotic rate and histologic features. Ki-67 proliferative index based on automated image analysis, tumor necrosis, nodal metastases, local or distant recurrence, and survival were compared across groups.

RESULTS

The mean mitotic count and Ki-67 index for TC, AC, and LCNEC were 0.1 and 2.3%, 3.4 and 16.8%, and 56.1 and 81.3% respectively. The Ki-67 index did not overlap among groups, with ranges of 0-6.7% for TC, 9.9-25.7% for AC, and 63.2-91.9% for LCNEC. Nodal metastases were identified in 4/39 (10%) TC, 2/7 (22%) AC, and 2/8 (25%) LCNEC. There was no survival difference between TC and AC, but there was a significant survival difference between LCNEC and TC and AC combined (p<0.001). There was a step-wise increase in disease free survival with tumor grade: no TC recurred, 2/7 AC recurred or progressed (median interval 35.5 months), and all LCNEC recurred or progressed (median interval 10.1 months). No patient with TC or AC died of disease, compared to 7/8 LCNEC with follow-up data.

CONCLUSIONS

We conclude that Ki-67 index is a useful diagnostic marker for neuroendocrine tumors, with 7% a divider between AC and TC, and 50% a divider between LCNEC and AC. LCNEC is biologically different from AC and TC, with a much more aggressive course, and a high Ki-67 index.

VIRTUAL SLIDES

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/13000_2014_174.

Unraveling tumor grading and genomic landscape in lung neuroendocrine tumors

Currently, grading in lung neuroendocrine tumors (NETs) is inherently defined by the histological classification based on cell features, mitosis count, and necrosis, for which typical carcinoids (TC) are low-grade malignant tumors with long life expectation, atypical carcinoids (AC) intermediate-grade malignant tumors with more aggressive clinical behavior, and large cell NE carcinomas (LCNEC) and small cell lung carcinomas (SCLC) high-grade malignant tumors with dismal prognosis. While Ki-67 antigen labeling index, highlighting the proportion of proliferating tumor cells, has largely been used in digestive NETs for assessing prognosis and assisting therapy decisions, the same marker does not play an established role in the diagnosis, grading, and prognosis of lung NETs. Next generation sequencing techniques (NGS), thanks to their astonishing ability to process in a shorter timeframe up to billions of DNA strands, are radically revolutionizing our approach to diagnosis and therapy of tumors, including lung cancer. When applied to single genes, panels of genes, exome, or the whole genome by using either frozen or paraffin tissues, NGS techniques increase our understanding of cancer, thus realizing the bases of precision medicine. Data are emerging that TC and AC are mainly altered in chromatin remodeling genes, whereas LCNEC and SCLC are also mutated in cell cycle checkpoint and cell differentiation regulators. A common denominator to all lung NETs is a deregulation of cell proliferation, which represents a biological rationale for morphologic (mitoses and necrosis) and molecular (Ki-67 antigen) parameters to successfully serve as predictors of tumor behavior (i.e., identification of pathological entities with clinical correlation). It is envisaged that a novel grading system in lung NETs based on the combined assessment of mitoses, necrosis, and Ki-67 LI may offer a better stratification of prognostic classes, realizing a bridge between molecular alterations, morphological features, and clinical behavior.

Analysis on the characteristics and prognosis of pulmonary neuroendocrine tumors

OBJECTIVE

To retrospectively review the clinical characteristics and analyze the prognostic factors of Chinese patients with pulmonary neuroendocrine tumors.

MATERIALS AND METHODS

The clinical data of 176 patients with pulmonary neuroendocrine tumors in Chinese PLA General Hospital from Mar., 2000 to Oct., 2012 were retrospectively analyzed. The parameters were evaluated by univariate and multivariate analysis, including the gender, age, smoking history, family history, TNM staging, localization (central or peripheral), tumor size, nodal status, histological subtype and treatment (operation or non-operation).

RESULTS

There were 23 patients with typical carcinoids (TC) (13.1%), 41 with atypical carcinoids (AC) (23.3%), 10 with large cell neuroendocrine carcinoma (LCNEC) (5.7%) and 102 with small cell lung cancer (SCLC) (57.9%). The median follow-up time was 64.5 months for AC, 38 months for LCNEC and 27 months for SCLC. The typical carcinoid censored data was 18 (more than 50% of the patients), so the median follow-up time was not obtained, and actuarial 5-year survivals for TC, AC, LCNEC and SCLC were 75.1%, 51.7%, 26.7% and 38.8%, respectively. COX univariate analysis revealed that the age (P=0.001), histological subtype (P=0.005), nodal status (P=0.000), treatment (P=0.000) and TNM staging (P=0.000) were the prognostic factors of the patients with pulmonary neuroendocrine tumors, whereas its multivariate analysis showed that only the age(P=0.001), TNM staging (P=0.002) and treatment (P=0.000) were independent prognostic factors.

CONCLUSIONS

Radical surgery remains the treatment of choice, and is the only curative option. The age, TNM staging and treatment are confirmed to be the independent prognostic factors in multivariable models for pulmonary neuroendocrine tumors.

Prognostic impact of diagnosing colorectal neuroendocrine carcinoma using the World Health Organization 2010 classification

BACKGROUND

Neuroendocrine carcinomas (NECs) arising in the large intestine are rare neoplasms with highly aggressive behavior. The aim of the study was to compare the 2000 and 2010 World Health Organization (WHO) classification of these colorectal NECs.

METHODS

We conducted a retrospective study of patients diagnosed with colorectal NECs according to the WHO 2000 classification who underwent surgery at the Asan Medical Center between May 2000 and December 2010. The data were reevaluated to assess their consistency with the WHO 2010 classification.

RESULTS

For 20 of the 34 patients (59%), the 2000 and 2010 WHO classifications yielded the same NEC diagnosis (NEC group), whereas for 14 of the 34 patients (41%), the WHO 2010 classification mandated a diagnosis of G1 or G2 neuroendocrine tumors (NETs) rather than NECs (G1/G2 NET group). The NEC group was older than the G1/G2 NET group (64 vs 55 years; P = .05). Tumor differentiation in the NEC group was poorer than in the G1/G2 NET group (percentage of poorly differentiated tumor, 70% vs 7%; P < .001). In both groups based on the 7th American Joint Committee on Cancer staging, most of the tumors were advanced at the time of diagnosis, reaching stage IIIB (6 NEC vs 10 NET) and stage IV (10 NEC vs 3 NET). The 5-year overall survival in the 2 groups was different (P = .02), but not the 5-year disease-free survival (P = .24).

CONCLUSION

These results indicate that the WHO 2010 classification of colorectal NEC is more accurate and has better prognostic value than the WHO 2000 classification.

Prognostic significance of Ki-67 expression in rectal carcinoid tumors

BACKGROUND/AIMS

Rectal carcinoid tumors can be resected with endoscopy, and it is important to assess their prognostic factors. We evaluated the potential of Ki-67 expression as a prognostic factor in rectal carcinoid tumors.

METHODS

We retrospectively reviewed the medical records of 37 patients with rectal carcinoid tumors who got endoscopic resection from January 2001 to January 2011 at Inje University Seoul Paik Hospital. We analyzed their endoscopic and histologic findings, Ki-67 expression, clinical outcome, and prognosis.

RESULTS

The mean age (±SD) of the patients was 56.3±10.7 years, and the male : female ratio was 3.6 : 1. The mean tumor size was 0.5±0.4 cm, 33 patients showed grade 1 tumors (89.2%) and the average Ki-67 expression was 0.7±1.2%. Thirty five patients underwent endoscopic mucosal resection, and two required endoscopic submucosal dissection. Eight patients had positive margins after resection, but no cases of lymphovascular invasion were identified. The median follow-up duration was 21.4±25.4 months, and no recurrences were observed.

CONCLUSIONS

In low grade rectal carcinoid tumors which are lack of central depression on colonoscopy, the expression of a molecular marker of malignant potential, Ki-67, was low. Therefore, endoscopic resection seemed to be a safe and effective treatment for these tumors.

Limited role of Ki-67 proliferative index in predicting overall short-term survival in patients with typical and atypical pulmonary carcinoid tumors

Pulmonary carcinoid tumors are currently classified as typical or atypical based on the mitotic index (2 per 10 hpf) and/or the presence of necrosis. Following incorporation of the Ki-67 index into the classification of GI carcinoid tumors, our oncologists have also been requesting this test as part of the work-up of pulmonary carcinoid tumors although there are currently no established criteria for interpreting Ki-67 index in these neoplasms. We utilized the Ariol(®) SL50 Image Analyzer system to measure the Ki-67 index in 101 pulmonary carcinoid tumors (78 typical and 23 atypical) and then correlated the Ki-67 index and the histological diagnoses in univariate and multivariable analysis with overall survival. The mean Ki-67 indices for the typical carcinoids (3.7 s.d.± 4.0) and the atypical carcinoids (18.8 s.d.± 17.1) were significantly different (P<0.001) although the frequency distributions of Ki-67 indices in the two groups overlapped considerably. Receiver operating characteristic curve analysis showed that a Ki-67 index cutoff value of 5% provided the best fit for specificity and sensitivity in predicting overall survival. Histological diagnosis and the Ki-67 index cutoff of 5% were each independently strong predictors of survival (P<0.001 and P=0.003, respectively). When considered together in multivariable analysis, histological diagnosis was the stronger predictor of overall survival and a Ki-67 index cutoff of 5% did not provide additional significant predictive survival information within either the typical carcinoid or the atypical carcinoid patient group. A few typical carcinoid patients with Ki-67 indices of 5% appeared to have worse survival after 5 years than those with Ki-67 indices <5%, but the data set was insufficiently powered to further analyze this. These findings do not provide best evidence for the routine use of Ki-67 index to prognosticate overall short-term survival in patients with pulmonary carcinoid tumors.

Clinicopathological and immunohistochemical analysis of spindle-cell carcinoid tumour of the lung

AIMS

To analyse the clinicopathological features and immunohistchemical profile of spindle-cell carcinoid tumours (SCCT) of the lung.

METHODS AND RESULTS

Using a cut-off value of ≥ 50% spindle cells for defining SCCT, 13 were indentified among 80 consecutively resected carcinoid cases. SCCTs are asymptomatic and are peripherally located, well-demarcated tumours. Tumour cells were composed of elongated spindle cells, with scant to moderate amounts of cytoplasm and uniform nuclei with fine granular chromatin. Immunohistochemical analysis revealed that all 13 cases were positive for three neuroendocrine markers (chromogranin A, synaptophysin and CD56). Four tumours (30.7%) were positive for broad-spectrum cytokeratin (CK) and nine tumours (69.2%) were positive for thyroid transcription factor 1. All epithelial components were negative for vimentin, but 12 tumours (92.3%) were positive for stellate-shaped cells (so-called sustentacular cells).

CONCLUSIONS

SCCTs are clinically asymptomatic, peripherally located, well-demarcated tumours, and patients with SCCTs have a favourable outcome. The immunoreactivity pattern of SCCT (low reactivity of broad-spectrum CK and reactivity for vimentin in intratumoral sustentacular cells) might result in a misdiagnosis of SCCT as mesenchymal tumour; therefore, pathologists need to be familiar with this pattern.

Using the mitosis-specific marker anti-phosphohistone H3 to assess mitosis in pulmonary neuroendocrine carcinomas

Counting mitotic figures (MFs) is one of the essential factors for determining the histologic grade of pulmonary neuroendocrine carcinoma (NEC). We analyzed MFs by using a mitotic-specific antibody of phosphohistone H3 (PHH3) in 113 lung NECs (66 typical carcinoids [TCs], 12 atypical carcinoids [ACs], 20 large cell NECs [LCNECs], and 15 small cell lung carcinomas [SCLCs]). Subdivided by histologic subtype, the mean PHH3-stained MFs (mPHMFs) were 0.09 per high-power field (hpf) in TCs, 0.39/hpf in ACs, 7.84/hpf in LCNECs, and 9.42 in SCLCs. From the 5-year overall survival rate for mPHMFs, an mPHMF of more than 1.0 was the best threshold in all NECs and an mPHMF of more than 0.4 was the best threshold for differentiating ACs from TCs. These values correspond to 4/10 hpf and 10/10 hpf. We showed that the PHH3-based mitosis-counting method is a reliable, easy method for counting mitoses in pulmonary NECs.

Oncocytic neuroendocrine tumors of the lung: histopathologic spectrum and immunohistochemical analysis of 15 cases

Oncocytic neuroendocrine tumor of the lung is rare. To reveal the clinicopathologic features of oncocytic neuroendocrine tumor, we reviewed surgical resections from 80 patients diagnosed with carcinoid tumors and 35 high-grade neuroendocrine carcinomas. We discovered 7 cases from the 80 carcinoid tumors and added 8 patients from personal consultation files. There were no statistically significant differences among the clinical features (such as age, location, and survival). Although most oncocytic neuroendocrine tumors were low-grade neuroendocrine carcinomas, we found that they could be of any grade. Tumor cells showed an ample amount of granular oncocytic cytoplasm and had a round-to-oval nucleus with coarse chromatin. Two cases mainly consisted of small-sized to medium-sized cells resembling plasma cells. This tumorous area intermingled with the conventional oncocytic area. Other histologic features were a large conspicuous nucleolus in 9 cases and the presence of giant cells in 8 cases. In the 80 carcinoid cases, bone formation (P = .034), the presence of giant cells (P = .021), and tumor cells with a conspicuous nucleolus (P = .021) were more frequently observed. Immunohistochemical analysis revealed that oncocytic cells were positive for antimitochondria antibody. In conclusion, most of the tumors were low-grade neuroendocrine carcinomas, but we found that oncocytic neuroendocrine tumor can display features of high-grade neuroendocrine carcinoma. The oncocytic change was induced by accumulation of mitochondria. Although this variant does not differ in clinical features of nononcocytic neuroendocrine tumors, histologic features of the oncocytic neuroendocrine tumor can be a potential cause of diagnostic error.

Sox10-positive sustentacular cells in neuroendocrine carcinoma of the lung

AIMS

Sustentacular cells are found in approximately half of pulmonary carcinoid tumours. However, most studies of sustentacular cells have used the less-specific antibody to the S100 protein, and any correlation between the presence of sustentacular cells and other clinicopathological factors is unclear. The aim of this study was to analyse the significance of sustentacular cells in pulmonary neuroendocrine carcinomas (NECs).

METHODS AND RESULTS

A Sox10 antibody was used to investigate 113 pulmonary NECs. Sustentacular cells were observed in 66.7% of typical carcinoid (TC) and 58.3% of atypical carcinoid (AC) cases, but not in high-grade NECs. Sustentacular-rich tumours had a statistically significant correlation with peripheral locations. We found no statistical differences in age, gender, smoking history, overall survival, or the occurrence of lymph node metastasis. In all but one case, when sustentacular cells were present in the primary site, they were also present in the metastatic lymph nodes. The presence of sustentacular cells differed in morphological subtypes, with the spindle pattern being the most common subtype.

CONCLUSIONS

Sox10-positive sustentacular cells were observed in carcinoid tumours but not in high-grade NECs. Sustentacular-rich carcinoid tumours did not show a correlation with the occurrence of lymph node metastasis or survival. The sustentacular cells found differed in morphological subtypes.

Partitioning of bronchopulmonary carcinoids in two different prognostic categories by ki-67 score

INTRODUCTION

Histological distinction between typical and atypical bronchopulmonary carcinoids is based on mitotic activity and necrosis. Regardless of these two parameters, outcome after surgery is often unpredictable. In this study the prognostic value of different clinico-pathological factors was retrospectively analyzed in a large series of patients with bronchopulmonary carcinoid.

MATERIALS AND METHODS

The long-term post-surgical outcome of 106 radically treated patients affected by bronchopulmonary carcinoid from two Italian centers was correlated with tumor characteristics assessed by combining conventional histology with a panel of immunohistochemical markers of neuroendocrine differentiation (chromogranin-A, NSE) and proliferation activity (Ki-67 score).

RESULTS

Carcinoids were assessed as typical (TC = 75; 70.8%) and atypical (AC = 31; 29.2%). Mean follow-up was 8.3 years (range: 0-20; median: 8.0). All cases expressed neuroendocrine markers. At univariate analysis, tumor recurrence [14/75 TC (18.7%), 15/31 AC (48.4%)] correlated with carcinoid histotype (P = 0.003), tumor size (P = 0.012), mitotic index (P = 0.044), Ki-67 score (P < 0.0001), and synchronous node metastasis (P = 0.037). Of these, Cox multivariate analysis confirmed only Ki-67 score as independent predictor of disease recurrence (P = 0.009). The best cut-off for Ki-67 score (calculated by ROC curves) discriminating recurrent vs non-recurrent disease was 4% (sensitivity 79.3%; specificity 83.8%; area under the curve 0.85). By stratifying patients according to this cut-off, a significantly different disease-free survival was found (log-rank test P < 0.0001).

CONCLUSION

Ki-67 score accurately separates bronchopulmonary carcinoids in two well-distinct histo-prognostic categories. Ki-67 score predicts the patients outcome better than mitotic count, histotype, and tumor stage and it is therefore helpful in establishing the appropriate follow-up.

Neuroendocrine tumors of the lung: an update

CONTEXT

The 2004 World Health Organization (WHO) classification recognizes 4 major types of lung neuroendocrine tumors: typical carcinoid, atypical carcinoid, small cell lung cancer, and large cell neuroendocrine carcinoma. Markedly different prognostic implications and treatment paradigms for these tumors underscore the importance of accurate pathologic diagnosis.

OBJECTIVE

To detail the clinical and pathologic features of lung neuroendocrine tumors, with emphasis on diagnostic criteria, differential diagnoses, and application of immunohistochemistry. The emerging evidence for the utility of Ki-67 (MIB1) in the diagnosis of lung neuroendocrine tumors, particularly in small biopsy and cytology, is emphasized.

DATA SOURCES

The 2004 WHO classification, other published literature, and primary material from the author's institution.

CONCLUSIONS

The current WHO classification of neuroendocrine tumors is based on morphologic features in combination with precisely defined mitotic rate and absence or presence of necrosis. Ki-67 (MIB1) is emerging as a useful ancillary tool in the diagnosis of these tumors. Continued research efforts are needed to identify additional immunohistochemical and molecular biomarkers that can serve as ancillary diagnostic tools and as potential therapeutic targets for these diseases.

[Retrospective study of clinicopathological characteristics in bronchopulmonary carcinoid]

背景与目的

支气管肺类癌（bronchopulmonary carcinoid, BPC）占全部肺原发性恶性肿瘤不到2%，相关研究报道较少，本研究拟分析BPC的总体及其两个亚型——典型类癌（typical carcinoid, TC）和不典型类癌（atypical carcinoid, AC）的临床、病理学特点。

方法

回顾性分析中山大学肿瘤防治中心1994年1月-2009年6月收治的28例BPC的临床资料，调取可再行切片的病理蜡块，重新切片染色及病理玻片会诊，分析BPC的总体及其亚型的临床特征和相关免疫组化指标与预后的关系。

结果

全部28例患者的总体5年生存率为56%，TC的5年生存率为70%，AC为41%，单因素分析示TNM分期（P=0.037)、有无淋巴结转移（P=0.001）、Ki-67核阳性数是否大于5%（P=0.009）是BPC总体的预后因素。相关性分析示BPC亚型与CD99、Bcl-2及Ki-67的表达具有相关性（P值分别0.017、0.043、0.033）。20例行肺癌根治性手术患者的5年生存率为73%，TC的5年生存率为83%，AC为57%。单因素分析示BPC亚型（P=0.013）、术后有无淋巴结转移（P=0.004)、Ki-67核阳性数是否大于5%（P=0.006）、TNM分期（P=0.047）是行肺癌根治性手术患者的预后因素。肿瘤复发（n=4）与Ki-67核阳性的表达和Bcl-2表达具有相关性（P值分别为0.027、0.045）。

结论

BPC是预后较好的肺原发性恶性肿瘤，Ki-67、Bcl-2的高表达是提示BPC复发及预后不良的影响因素，TNM分期是影响预后的独立因素，行根治性手术是主要的治疗手段。

ERCC1 and Ki67 in small cell lung carcinoma and other neuroendocrine tumors of the lung: distribution and impact on survival

BACKGROUND

Excision repair cross-complementation group 1 (ERCC1) is a key component of the platinum-DNA repair mechanism. Ki67 is associated with the clinical course of several malignancies. The associations of ERCC1 and Ki67, clinical features and survival in small cell lung carcinoma (SCLC), typical carcinoid (TC), atypical carcinoid (AC), and large cell neuroendocrine carcinoma (LCNEC) were determined.

MATERIALS AND METHODS

We included a consecutive series of 186 patients with SCLC treated with platinum-based chemotherapy and surgically treated patients with TC (n = 48), AC (n = 15) and LCNEC (n = 27). ERCC1 and Ki 67 were measured by immunohistochemistry and scored using published criteria.

RESULTS

The expression of ERCC1 was different among the different tumor types (p < 0.001). For patient with limited disease as well as extensive disease SCLC, no association of ERCC1 expression with survival was observed (p = 0.59). However, only 10% of SCLC tumors expressed ERCC1. For TC and AC, ERCC1 positive patients had better survival than ERCC1 negative patients. ERCC1 had no prognostic impact for LCNEC. A difference of the percentage of Ki67 LI was observed for the different tumor types (p < 0.001). The difference between TC and AC was significant (p = 0.02), as was the difference between low grade (TC+AC) and high grade NE (LCNEC + SCLC) (p < 0.001). For all included patients, a correlation between Ki67 and ERCC1 was observed (RSquare = 0.19, p < 0.001).

CONCLUSION

ERCC1 expression in SCLC treated with platinum-based chemotherapy has no impact on survival. High expression of ERCC1 in TC might represent a clue to the failure of platinum-based therapy in these patients. ERCC1 expression has prognostic impact in lung carcinoids. Ki 67 might be considered as a supplementary test to the histopatologic classification of NE tumors.

Correlation between grade and prognosis in metastatic gastroenteropancreatic neuroendocrine tumors

Three-tiered grading systems (low, intermediate, and high grade) have been proposed for neuroendocrine tumors. These classifications have not been rigorously evaluated in neuroendocrine malignancies of the digestive tract. We performed a retrospective chart analysis of 83 patients with metastatic gastroenteropancreatic neuroendocrine tumors, correlating tumor grade with overall survival. We also analyzed available biopsy specimens (on 40 patients), examining hematoxylin and eosin stains for mitotic rate and immunostaining for measurement of the Ki-67 index. Tumor grades were assigned based on the mitotic rate and the Ki-67 index, and the prognostic validity of each grading method was assessed. A highly significant correlation existed between the reported tumor grade and overall survival. Five-year survival rates for patients with low-, intermediate-, and high-grade tumors were 87%, 38%, and 0%, respectively. On biopsy specimen analysis, both mitotic rates and Ki-67 indexes correlated strongly with overall survival. We conclude that a 3-tiered grading classification for gastroenteropancreatic neuroendocrine tumors correlates with survival in the metastatic setting. Both mitotic rates and Ki-67 indexes are inversely associated with survival and can be analyzed independently for assignment of grade.

Neuroendocrine carcinomas of the lung: a critical analysis

Neuroendocrine carcinomas represent an important group of primary neoplasms in the lung. During the last decades, the nomenclature of these tumors has evolved and the current use of immunohistochemical and molecular biology studies have, to some extent, expanded the conventional view of these tumors. However, the primary diagnosis of most of these lesions is performed on limited biopsy specimens, which may not translate well when one is confronted with a nomenclature that is based on resected material. In addition, for some of these specific entities, some confusion and controversy apparently remain, allowing for the proliferations of different terms that, although they may be dismissed as "semantics," may have a role in interpretation, further subclassification, and, possibly, treatment. Herein we review current concepts regarding the classification of these neoplasms and the role of this classification in our daily practice and discuss how it may impact treatment.

Immunohistochemistry of pulmonary and pleural neoplasia

CONTEXT

The use of immunohistochemical stains has several applications in the evaluation of pulmonary and pleural neoplasms. The number of available immunohistochemical stains is continually expanding and, although these stains are an important diagnostic adjunct, their use is not without limitations and pitfalls.

OBJECTIVE

To review and summarize the primary immunohistochemical applications with regard to the most common pulmonary and pleural neoplasms and discuss newly developed markers and common pitfalls.

DATA SOURCES

Pertinent peer-reviewed literature emphasizing immunohistochemical applications in common lung and pleural tumors, unusual and problematic staining patterns in frequently encountered subtypes/histologic variants, and recently developed immunohistochemical stains of potential promise.

CONCLUSIONS

Immunohistochemical stains provide the greatest aid in establishing the site of origin of adenocarcinomas encountered in the lung and in separating epithelioid mesothelioma from adenocarcinoma. Certain subtypes of pulmonary adenocarcinomas may exhibit unusual staining patterns that may be potentially problematic. Immunohistochemistry has a more limited role in separating small cell carcinoma from non-small cell carcinoma, and extreme caution must be used in the situation of crushed biopsy specimens.

Usefulness of Ki-67 for predicting the metastatic potential of rectal carcinoids

Rectal carcinoid <10 mm can be completely removed by endoscopic procedure. However, a few authors reported that small rectal carcinoids have the potential to metastasize. Therefore, histological parameters predicting their metastatic potential are necessary. The aim of the present study was to evaluate the usefulness of Ki-67 positive/negative area ratio (Ki-67 ratio) using computer-assisted image analysis. A total of 43 patients with rectal carcinoids were retrospectively investigated. Twenty-eight patients underwent endoscopic resection and 15 patients underwent surgery. Nine of the 43 patients presented with metastatic disease. The Ki-67 ratio of all specimens was measured. Finally, the Ki-67 ratio was compared with other macroscopic or microscopic parameters for predicting lymph node or distant metastatic disease. The mean Ki-67 ratio of the metastatic and non-metastatic group was 3.9 and 1.0%, respectively (P < 0.01). The Ki-67 ratio was effective because of its high sensitivity (88.9%) and specificity (82.4%). Ki-67 ratio was superior to other microscopic parameters such as variation in nuclear size and vessel permeation. Ki-67 ratio was as effective as the other macroscopic parameters of tumor size and central depression. Based on these results it is suggested that Ki-67 is a reliable microscopic marker to predict metastatic potential of rectal carcinoids.

Well-Differentiated Neuroendocrine Carcinomas: The Spectrum of Histologic Subtypes and Various Clinical Behaviors

The term "well-differentiated neuroendocrine carcinoma" was coined to describe a variety of demonstrably neuroendocrine tumors which were more aggressive (both with respect to their histologic appearance and their clinical course) than (typical) bronchial carcinoids but were also clearly distinguishable from small cell neuroendocrine carcinomas. This umbrella term encompasses a variety of tumors previously described by a variety of terms including "atypical" carcinoids, "malignant tumorlets," peripheral stage I small-cell carcinoma, as well as neoplasms described simply as "undifferentiated carcinoma" (prior to the recognition of their neuroendocrine properties). As such, this term is a broad term and is not simply synonymous with "atypical carcinoid." Over time, at least 3 subtypes have been identified based upon their histologic appearance and mitotic index, with correspondingly aggressive clinical courses.

Tumeurs neuroendocrines thoraciques

Neuroendocrine pulmonary and thymic tumors constitute a distinct category of tumors collectively disclosing morphologic and biologic neuroendocrine features. They are classified in 4 histopathological types and 3 malignancy grades. The typical carcinoids are of low grade, the atypical carcinoids of intermediate grade and the large cell neuroendocrine carcinoma with the small cell carcinoma are high grade neuroendocrine tumors. Their distinction relies on objective morphologic and phenotypic criteria of strong clinical significance and predictive prognostic value.