Pulmonary Neuroendocrine Tumors

Head-to-head: Should Ki67 proliferation index be included in the formal classification of pulmonary neuroendocrine neoplasms?

The reporting of lung neuroendocrine neoplasms (NENs) according to the 2021 World Health Organisation (WHO) is based on mitotic count per 2 mm2, necrosis assessment and a constellation of cytological and immunohistochemical details. Accordingly, typical carcinoid and atypical carcinoid are low- to intermediate-grade neuroendocrine tumours (NETs), while large-cell neuroendocrine carcinoma (NEC) and small-cell lung carcinoma are high-grade NECs. In small-sized diagnostic material (cytology and biopsy), the noncommittal term of carcinoid tumour/NET not otherwise specified (NOS) and metastatic carcinoid NOS have been introduced with regard to primary and metastatic diagnostic settings, respectively. Ki-67 antigen, a well-known marker of cell proliferation, has been included in the WHO classification as a non-essential but desirable criterion, especially to distinguish NETs from high-grade NECs and to delineate the provisional category of carcinoid tumours/NETs with elevated mitotic counts (> 10 mitoses per mm2) and/or Ki-67 proliferation index (≥ 30%). However, a wider use of this marker in the spectrum of lung NENs continues to be highly reported and debated, thus witnessing a never-subsided attention. Therefore, the arguments for and against incorporating Ki-67 in the classification and clinical practice of these neoplasms are discussed herein in detail.

Combined large‑cell neuroendocrine carcinoma and small‑cell lung cancer: A case report

Combined large-cell neuroendocrine carcinoma (LCNEC) and small-cell lung cancer (SCLC) is extremely rare, with only a few reports available in the literature. An accurate diagnosis is difficult to make due to the overlapping clinical features between LCNEC and SCLC, and a standardized treatment option is lacking. A 53-year-old female patient was admitted to Xiaoshan Affiliated Hospital of Wenzhou Medical University (Hangzhou, China) due to symptoms of dyspnea and phlegm, with blood in the sputum. Computed tomography revealed a 52×32×26-mm irregular soft-tissue mass in the left upper lung. Pathological examination of the biopsy specimen showed a poorly differentiated neuroendocrine carcinoma with compression injury, consistent with a mixed type of large and small cell carcinoma. The patient was administered chemotherapy, radiotherapy and targeted therapy, and as of October 2023, the patient had a survival period of 29 months. LCNEC combined with SCLC is a sporadic tumor with a high potential for malignancy. Multidisciplinary treatment and close follow-up are recommended. The multidisciplinary treatment strategy used in the present study is expected to help inform future therapeutic decisions.

Expression patterns of novel immunotherapy targets in intermediate- and high-grade lung neuroendocrine neoplasms

BACKGROUND

Advancements in immunotherapeutic approaches only had a modest impact on the therapy of lung neuroendocrine neoplasms (LNENs). Our multicenter study aimed to investigate the expression patterns of novel immunotherapy targets in intermediate- and high-grade LNENs.

METHODS

The expressions of V-domain Ig suppressor of T cell activation (VISTA), OX40L, Glucocorticoid-induced TNF receptor (GITR), and T cell immunoglobulin and mucin domain 3 (TIM3) proteins were measured by immunohistochemistry in surgically resected tumor samples of 26 atypical carcinoid (AC), 49 large cell neuroendocrine lung cancer (LCNEC), and 66 small cell lung cancer (SCLC) patients. Tumor and immune cells were separately scored.

RESULTS

Tumor cell TIM3 expression was the highest in ACs (p < 0.001), whereas elevated tumor cell GITR levels were characteristic for both ACs and SCLCs (p < 0.001 and p = 0.011, respectively). OX40L expression of tumor cells was considerably lower in ACs (vs. SCLCs; p < 0.001). Tumor cell VISTA expression was consistently low in LNENs, with no significant differences across histological subtypes. ACs were the least immunogenic tumors concerning immune cell abundance (p < 0.001). Immune cell VISTA and GITR expressions were also significantly lower in these intermediate-grade malignancies than in SCLCs or in LCNECs. Immune cell TIM3 and GITR expressions were associated with borderline prognostic significance in our multivariate model (p = 0.057 and p = 0.071, respectively).

CONCLUSIONS

LNEN subtypes have characteristic and widely divergent VISTA, OX40L, GITR, and TIM3 protein expressions. By shedding light on the different expression patterns of these immunotherapy targets, the current multicenter study provides support for the future implementation of novel immunotherapeutic approaches.

Current understanding of pathogenetic mechanisms in neuroendocrine neoplasms

INTRODUCTION

Despite the fact that important advances in research on neuroendocrine neoplasms (NENs) have been made, consistent data about their pathogenetic mechanism are still lacking. Furthermore, different primary sites may recognize different pathogenetic mechanisms.

AREAS COVERED

This review analyzes the possible biological and molecular mechanisms that may lead to NEN onset and progression in different organs. Through extensive research of the literature, risk factors including hypercholesterolemia, inflammatory bowel disease, chronic atrophic gastritis are evaluated as potential pathogenetic mechanisms. Consistent evidence is available regarding sporadic gastric NENs and MEN1 related duodenopancreatic NENs precursor lesions, and genetic-epigenetic mutations may play a pivotal role in tumor development and bone metastases onset. In lung neuroendocrine tumors (NETs), diffuse proliferation of neuroendocrine cells on the bronchial wall (DIPNECH) has been proposed as a premalignant lesion, while in lung neuroendocrine carcinoma nicotine and smoke could be responsible for carcinogenic processes. Also, rare primary NENs such as thymic (T-NENs) and Merkel cell carcinoma (MCC) have been analyzed, finding different possible pathogenetic mechanisms.

EXPERT OPINION

New technologies in genomics and epigenomics are bringing new light to the pathogenetic landscape of NENs, but further studies are needed to improve both prevention and treatment in these heterogeneous neoplasms.

Incidence and prognostic nomogram for resected non-small cell neuroendocrine tumor: A population-based respective study in China and the SEER database

Background

Pulmonary neuroendocrine tumors, including small cell lung cancer (SCLC) and non-small cell neuroendocrine tumor (NSCLC-NET), have obvious heterogeneity. The comparison between SCLC and NSCLC-NET, and prognostic nomogram of resected NSCLC-NET have not been performed.

Methods

We retrieved data from SEER database. The incidence and prognostic factors were compared between SCLC and NSCLC-NET. By Cox regression, we constructed prognostic nomogram of resected NSCLC-NET. The nomogram was evaluated by ROC, calibration plot and decision curve analysis (DCA) and compared with 8th TNM staging system. A Chinese cohort was used for external validation.

Results

The age-adjusted incidence of SCLC declined after 1991 but the incidence of NSCLC-NET continuously rose. Patients with typical carcinoid had the best prognosis in both overall survival and lung cancer specific survival, followed by atypical carcinoid, large cell neuroendocrine tumor and SCLC after operation. Patients receiving sleeve resection in NSCLC-NET had longer survival but segmental resection was more recommended in SCLC. High-smoking index was associated with worse overall survival in both SCLC and NSCLC-NET. Histological subtype, age, surgery type, N, M stage and chemotherapy were independent prognostic factors and used to construct prognostic nomogram of resected NSCLC-NET. The nomogram performed well with good discrimination, calibration and clinical usefulness, which was validated by a Chinese cohort (1, 3, 5-year AUC: SEER cohort 0.873, 0.901, 0.875; Chinese cohort 0.867, 0.892, 0.874). Compared to the 8th staging system, the nomogram had higher C-index (0.87 vs 0.728, P < 0.001), clinical usefulness, increasing AUC value over time and improved 68%.

Conclusion

The prognostic nomogram of resected NSCLC-NET performed better than the 8th TNM staging system. It may have certain value in risk stratification and survival prediction of patients with resected NSCLC-NET and help clinicians to take measures for high-risk patients in advance.

Carcinoid tumors outside the abdomen

Neuroendocrine tumors (NETs) are epithelial malignancies that can arise from multiple tissues. Gastrointestinal (GI) NETs are the most common; in this review of extra-abdominal carcinoid tumors, we focus our discussion on bronchial and thymic carcinoid tumors. Bronchial carcinoid tumors comprise a quarter of all NETs and less than 2% of all lung cancers. Thymic carcinoid tumors are extremely rare, accounting for 5% of thymic tumors. Both bronchial and thymic carcinoid tumors are histologically classified as either typical or atypical based on their mitotic rate (less than 2 or 2-10 mitoses per 10 high-powered fields (HPF), respectively). Both bronchial and thymic carcinoids can present with symptoms of obstruction and potentially carcinoid syndrome. The gold standard of management of bronchial and thymic carcinoid tumors is surgical resection. For patients with advanced disease, first-line systemic therapy is generally somatostatin analog monotherapy with octreotide or lanreotide. In patients with refractory disease, therapy generally involves peptide receptor radioligand therapy, everolimus, or cytotoxic chemotherapy. There are ongoing, prospective trials comparing the mainstays of systemic therapy for these patients, as well as ongoing evaluations of immune checkpoint inhibitors and multi-kinase inhibitors. Prognosis for both bronchial and thymic carcinoid tumors depends on histologic grade, local versus invasive disease, and extent of metastases. Herein we provide a summary of the pathophysiologic and clinical background, the current state of the field in diagnosis and management, and note of key ongoing prospective trials for patients with bronchial and thymic carcinoid tumors.

Small-cell lung cancer brain metastasis: From molecular mechanisms to diagnosis and treatment

Lung cancer is the most malignant human cancer worldwide, also with the highest incidence rate. However, small-cell lung cancer (SCLC) accounts for 14 % of all lung cancer cases. Approximately 10 % of patients with SCLC have brain metastasis at the time of diagnosis, which is the leading cause of death of patients with SCLC worldwide. The median overall survival is only 4.9 months, and a long-tern cure exists for patients with SCLC brain metastasis due to limited common therapeutic options. Recent studies have enhanced our understanding of the molecular mechanisms leading to meningeal metastasis, and multimodality treatments have brought new hopes for a better cure for the disease. This review aimed to offer an insight into the cellular processes of different metastatic stages of SCLC revealed by the established animal models, and into the major diagnostic methods of SCLC. Additionally, it provided in-depth information on the recent advances in SCLC treatments, and highlighted several new models and biomarkers with promises to improve the prognosis of SCLC.

The Ki-67 antigen in the new 2021 World Health Organization classification of lung neuroendocrine neoplasms

Prof. Rosai's work has permeated the surgical pathology in many fields, including the 2017 World Health Organization classification on tumors of endocrine organs and pulmonary neuroendocrine cell pathology, with stimulating contributions which have also anticipated the subsequent evolution of knowledge. Among the many studies authored by Prof. Rosai, we would like to recall one of which whose topic has been encased in the new 2021 World Health Organization classification on lung tumors. This is an eminently practical paper dealing with the use of the proliferation antigen Ki-67 in lung neuroendocrine neoplasms. While these neoplasms are primarily ranked upon histologic features and Ki-67 labeling index does not play any role in classification, diagnostic dilemmas may however arise in severely crushed biopsy or cytology samples where this marker proves helpful to avoid misdiagnoses of carcinoids as small cell carcinoma. Another application of Ki-67 labeling index endorsed by the 2021 World Health Organization classification regards, alongside mitotic count, the emerging recognition of lung atypical carcinoids with increased mitotic or proliferation rates, whose biological boundaries straddle a subset of large cell neuroendocrine carcinoma.

This article focuses on these two practical applications of the proliferation marker Ki-67 in keeping with the 2021 World Health Organization classification, which provides standards for taxonomy, diagnosis and clinical decision making in lung neuroendocrine neoplasm patients.

Small Cell Neuroendocrine Carcinoma of the Lacrimal Sac Presenting with Lacrimal Duct Obstruction

Purpose: We report a case of primary small cell neuroendocrine carcinoma arising from the lacrimal sac. Case summary: A 54-year-old man presented with epiphora that had been present for 1 month. He underwent lacrimal syringe analysis of the lower punctum in the right eye, which demonstrated fluid regurgitation from the upper punctum. Computed tomography revealed a 3.0 × 3.4 × 3.0 cm mass with an ill-defined margin in the right lacrimal sac, which demonstrated invasion of the lacrimal duct and bony destruction of the inferior and medial orbital walls. Incisional biopsy and histologic examination showed that the tumor was composed of small round tumor cells. On the basis of histopathological and immunohistochemical evaluations, a diagnosis of small cell neuroendocrine carcinoma was made. The patient received chemotherapy.Conclusions: To the best of our knowledge, this is the first case of primary small cell neuroendocrine carcinoma arising from the lacrimal sac in Korea. Small cell neuroendocrine carcinoma in the lacrimal sac should be regarded as a differential diagnosis for patients with a nasolacrimal duct obstruction.

Clinicopathological analysis of primary carcinoid tumour of the ovary arising in mature cystic teratomas

OBJECTIVE

To investigate the clinicopathological features, diagnosis and differential diagnosis of patients with primary ovarian carcinoid tumours arising in mature cystic teratomas.

METHODS

This retrospective case series analysed the data from patients with primary ovarian carcinoid tumours arising in mature cystic teratomas.

RESULTS

The study enrolled four patients. Histopathological analysis of the tumours identified the following subtypes: insular (n = 1), trabecular (n = 1) and strumal (n = 2). All four primary ovarian carcinoid tumours originated from a mature teratoma. The morphology of the primary ovarian carcinoids was similar to other neuroendocrine tumours. Strumal carcinoids were composed of different proportions of thyroid tissue intimately admixed with carcinoid tumour. Tumour tissue was arranged in insular and/or trabecular patterns. The nucleus of tumour cells displayed exquisite chromatin without obvious mitotic figures. Tumour tissues were positively stained for neuroendocrine markers chromogranin A, synaptophysin and CD56 to varying degrees. Strumal carcinoid tumours were cytokeratin 19 positive and thyroid transcription factor 1 negative. No recurrence or metastasis occurred during follow-up (12-71 months).

CONCLUSION

Primary ovarian carcinoid tumours arising in mature cystic teratomas are rare. Diagnosis and differential diagnosis should be confirmed by clinical features, histopathological characteristics and specific immunophenotyping.