Clinicopathological Features of Neuroendocrine Tumors in Gastroenteropancreatic Tract: A Single Center Study

Abstract

Background: Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) are a heterogeneous group of tumors with varying biological, functional, and clinical characteristics that develop from the gastroenteropancreatic tract's diffuse neuroendocrine system. The objective of this study is to determine the clinicopathological features of GEP-NETs at our facility.

Methodology: A cross-sectional analysis of 87 biopsies and resection specimens from January 2020 to January 2022 was performed. The histopathological reports as well as patient's demographic and clinic pathological data were obtained. Two pathologists with a special interest in gastroenteropancreatic pathology blindly reviewed all cases. The tumor grade and stage were determined using the WHO classification (2019) and the AJCC TNM system (8th edition). The data were analyzed with SPSS version 22 (IBM Corp., Armonk, NY, USA).

Results: Of the total 87 patients, 49 (56.3%) were male. The age range was 11 to 80 years, with a mean of 45.7±16.4 and the majority (56.3%) were under 50 years. The most frequent symptom was abdominal pain (55.2%). The most common site of GEP-NETs was the appendix (21.8%), followed by the ileum (18.4%), with the majority of tumors being non-functional (96.5%). Furthermore, neuroendocrine tumor (NET) grade 1 accounts for 62% of the total, followed by NET grade 2 (24.1%), neuroendocrine carcinoma (NET) grade 3 (10.3%), and mixed neuroendocrine-non-neuroendocrine neoplasms (MINENs) (3.5%). Synaptophysin was found to be positive in 83.9% cases while Chromogranin A was positive in 39.1%. A pathologic tumor (pT) stage was determined in 47 resection specimens in our study and the most common stage was pT3 (36.1%). Nodal metastasis was found in 25.5% of patients.

Conclusions: According to our study, appendix and ileum were the most common GEP-NETs sites. The tumor site and grade were shown to significantly correlate among the clinicopathological features but there was no discernible correlation between the tumor grade and the gender, age, or pathological tumor (pT) stage.

Keywords: clinicopathological features; gastroenteropancreatic neuroendocrine tumors; grading; mixed neuroendocrine-non-neuroendocrine neoplasms; neuroendocrine tumors.

Figure 1. (A) H&E image at 400x magnification shows nested pattern in NET grade 1. (B) H&E image at 100x magnification shows NET grade 2. (C) H&E image at 40x magnification shows poorly differentiated tumor with necrosis in NEC grade 3. (D) H&E image at 40x magnification shows adenocarcinoma and neuroendocrine components in MINEN (black arrows).

H&E: hematoxylin and eosin; NET: neuroendocrine tumor; NEC: neuroendocrine carcinoma; MINEN: mixed neuroendocrine-non-neuroendocrine neoplasm.

Figure 2. (A) The image shows diffuse cytoplasmic staining of Synaptophysin. (B) Diffuse granular cytoplasmic staining of Chromogranin A. (C) Ki67 shows > 3% proliferation index, focal nuclear staining (black arrow). (D) The Image shows > 50% Ki67 proliferation index in NEC.

NEC: neuroendocrine carcinoma

Figure 3. Frequency of clinical symptoms in GEP-NETs patients (n=87)

GEP-NETs, gastroenteropancreatic neuroendocrine tumors

Figure 4. Distribution of GEP-NETs at various anatomical sites (n=87)

GEP-NETs, gastroenteropancreatic neuroendocrine tumors