Typical and atypical carcinoid tumors of the lung: a clinicopathological correlation of 783 cases with emphasis on histological features

Pathological & radiological variables in the diagnosis of bronchopulmonary carcinoids (BPCs) with a focus on Antigen Kiel 67 (Ki-67) proliferation index

BACKGROUND

Bronchopulmonary carcinoids (BPCs) are classified into typical carcinoids (TC) and atypical carcinoids (AC), based on the mitotic count and absence/presence of necrosis on pathology specimens. There are limitations to accurate measurement of these criteria. It important to study other markers like Ki-67, to enhance the diagnostic accuracy of lung carcinoids.

OBJECTIVE AND METHODOLOGY

Retrospective analysis of BPCs treated with surgery between 2012-2022, to examine the accuracy of Ki-67 on the diagnostic specimen, concordance of diagnostic and resection specimens, diagnostic accuracy of Positron Emission Tomography (PET) and concordance of clinical and pathological staging.

RESULTS

205 patients were included in the analysis (final diagnosis TC 180, AC 25). Mean age 60.5 years and 68 % female. Ki-67 (<5% vs. 5-30 %) on diagnostic biopsy, available in 64 % (n = 131) of the cohort, had specificity (diagnose TC correctly) of 89.4 % (95 %CI 80.4 %-94.7 %) and sensitivity (diagnose AC correctly) of 77.8 % (40.2 %-96.1 %). This compared to 97.5 % (90.3 %-99.6 %) and 36.4 % (12.4 %-68.4 %) for mitotic count (<2mitoses/2mm2 vs. 2-10mitoses/2mm2) and 100 % (94.4 %-100 %) and 21.4 % (5.7 %-51.2 %) for necrosis (absence vs. presence). A pre-resection diagnosis of TC (including surgical biopsy) shows better concordance with final diagnosis on resection specimen (94.9 %, 95 %CI 88.7 %-97.9 %, n = 117) as compared to the diagnosis of AC 83.3 % (95 %CI 50.9 %-97.1 %, n = 12). Concordance for AC appears higher with image guided lung biopsy 80 % (95 % CI, 29.9 %-98.9 %) than bronchoscopy 50 % (9.5 %-90.5 %). SUVmax on 18FDG-PET was a modest predictor of BPC sub-type with an AUC of 0.684 (95 % CI: 0.545,0.823). The clinical and pathological staging were concordant in 46 % (85/184) cases. However, 27 % (50/184) were upstaged and 13 % (23/172) found to have occult nodal metastases on pathology review of the surgical specimens.

CONCLUSION

The diagnosis and sub-typing of BPCs on diagnostic specimens is challenging. Our data suggest Ki-67 could increase diagnostic accuracy, but further research is needed to confirm this.

Prognostic nomogram for predicting long-term survival in bronchopulmonary carcinoid tumor patients receiving resection

Background

We analyzed bronchopulmonary carcinoid tumor (BPC) patients receiving resection from the Surveillance, Epidemiology, and End Results (SEER) database to identify the predictive factors of their survival. Then, we developed and validated nomograms to predict overall survival (OS) and cancer-specific survival (CSS) in BPC patients.

Methods

BPC patients registered in the SEER database were included. They were divided into a training set and an internal validation set (7:3). BPC patients from our center were included as an external validation set. Independent prognostic factors identified by a Cox regression model in the training set were used to construct nomograms to predict survival. Discrimination and calibration plots were used to evaluate the predictive accuracy of the nomograms. The nomograms were evaluated in both the internal and the external validation datasets.

Results

Age, pathological type, and N stage were identified as independent prognostic factors of OS and CSS by Cox analyses (all P<0.05). Tumor size ≥2.5 cm (P=0.045) was an independent factor for unfavorable CSS. Based on these variables, nomograms were constructed. All concordance indexes of the training set, internal validation set, and external validation set indicated that the nomograms had the preferable discriminatory ability. The calibration plots for predictions of the 1-, 3-, and 5-year OS and CSS were in excellent agreement.

Conclusions

Age, pathological type, N stage, and tumor size were independent predictive factors of prognosis in BPC patients receiving resection. These nomograms could serve as effective and accurate tools for the prognostic evaluation of patients with BPCs.

Lung carcinoid tumors with Diffuse Idiopathic Pulmonary NeuroEndocrine Cell Hyperplasia (DIPNECH) exhibit pejorative pathological features

INTRODUCTION

Diffuse Idiopathic Pulmonary NeuroEndocrine Cell Hyperplasia (DIPNECH) is a rare disease often associated with carcinoid tumors. We aimed at evaluating the impact of DIPNECH on characteristics and prognosis of patients who underwent radical treatment of pulmonary carcinoid tumors.

MATERIAL AND METHODS

We reviewed all patients operated on for curative-intent resection of carcinoid tumor in our department from 2001 to 2020. Cases exhibiting both pathological and radiological features of DIPNECH, as assessed by respective thoracic expert physicians, were analyzed separately.

RESULTS

172 cases of resected carcinoid tumors were identified, including 25 (14.5 %) harboring pathological criteria of DIPNECH and radiologic features like mosaic attenuation (92.0 %), multiple nodules < 5 mm (76.0 %), and mucoid impactions (32 %). In DIPNECH patients, major pulmonary resections were usually performed (92.0 %) and resected tumors were mostly classified as pT1 (92 %). Mean Ki67 staining was 3.7 ± 5.2 %. The early postoperative period was mostly uneventful (96.0 %) and 5-year survival was 92.9 ± 6.9 %. Compared to non-DIPNECH cases, we found that patients were older (mean 65.6 ± 9.3 versus 54.1 ± 17.9, p = 0.002), more frequently female (84.0 % versus 56.5 %, p = 0.009), and exhibiting diabetes mellitus (45.8 % versus 18.5 %, p < 0.001) or hypertension (45.8 % versus 24.1 %, p = 0.039). The rate of atypical carcinoid tumors was significantly higher in DIPNECH patients (40.0 % versus 19.9 %, p = 0.027), as well as rate of mediastinal lymph-nodes involvement (pN2+) (36.0 % versus 4.1 %, p < 0.001). At multivariate analysis, only DIPNECH pattern and atypical histology were independent factors of pN2 invasion which was the only predictor of poorer prognosis on Log-Rank test.

CONCLUSION

Carcinoid tumors with proven DIPNECH are associated with negative pathological features and may deserve a dedicated perioperative management.

Molecular Pathology of Well-Differentiated Pulmonary and Thymic Neuroendocrine Tumors: What Do Pathologists Need to Know?

Thoracic (pulmonary and thymic) neuroendocrine tumors are well-differentiated epithelial neuroendocrine neoplasms that are classified into typical and atypical carcinoid tumors based on mitotic index cut offs and presence or absence of necrosis. This classification scheme is of great prognostic value but designed for surgical specimens, only. Deep molecular characterization of thoracic neuroendocrine tumors highlighted their difference with neuroendocrine carcinomas. Neuroendocrine tumors of the lung are characterized by a low mutational burden, and a high prevalence of mutations in chromatin remodeling and histone modification-related genes, whereas mutations in genes frequently altered in neuroendocrine carcinomas are rare. Molecular profiling divided thymic neuroendocrine tumors into three clusters with distinct clinical outcomes and characterized by a different average of copy number instability. Moreover, integrated histopathological, molecular and clinical evidence supports the existence of a grey zone category between neuroendocrine tumors (carcinoid tumors) and neuroendocrine carcinomas. Indeed, cases with well differentiated morphology but mitotic/Ki-67 indexes close to neuroendocrine carcinomas have been increasingly recognized. These are characterized by specific molecular profiles and have an aggressive clinical behavior. Finally, thoracic neuroendocrine tumors may arise in the background of genetic susceptibility, being MEN1 syndrome the well-defined familial form. However, pathologists should be aware of rarer germline variants that are associated with the concurrence of neuroendocrine tumors of the lung or their precursors (such as DIPNECH) with other neoplasms, including but not limited to breast carcinomas. Therefore, genetic counseling for all young patients with thoracic neuroendocrine neoplasia and/or any patient with pathological evidence of neuroendocrine cell hyperplasia-to-neoplasia progression sequence or multifocal disease should be considered.