Clinicopathological features of primary gastric neuroendocrine neoplasms: A single-center analysis

Type 2 and type 3 gastric neuroendocrine tumors have high risk of lymph node metastasis: Systematic review and meta-analysis

OBJECTIVES

Lymph node metastasis (LNM) is crucial in determining treatment strategies for gastric neuroendocrine tumors (gNETs). While type 3 is considered more aggressive than types 1 and 2 within the clinical subtype of gNETs, the supporting data were insufficient, due to their rarity. We aimed to study the prevalence and risk factors associated with LNM in gNETs.

METHODS

We searched electronic databases from 1990 to 2023 to identify case-control and cohort studies regarding gNETs resected either endoscopically or surgically. The primary outcome measured was the pooled prevalence of LNM in gNETs. Secondary outcomes included categorizing the prevalence of LNM by clinical subtypes and identifying pathological risk factors associated with LNM in gNETs.

RESULTS

We included 28 studies, involving 1742 patients, among whom 240 had LNM (pooled prevalence rate, 11.8%; 95% confidence interval 7.6-17.9%). The pooled prevalence rates of LNM for type 1, type 2, and type 3 gNETs were 6.0%, 38.5%, and 23.2%, respectively. Type 2 (odds ratio [95% confidence interval] 11.53 [3.46-38.49]) and type 3 (6.88 [3.79-12.49]) gNETs exhibited a higher risk for LNM compared to type 1. Pathological risk factors for LNM included tumor size >10 mm (4.18 [1.91-9.17]), tumor invasion into the muscularis propria or deeper (11.21 [3.50-35.92]), grade 2/grade 3 (5.96 [2.65-13.40]), and lymphovascular invasion (34.50 [6.70-177.51]).

CONCLUSION

We demonstrated that type 2 gNETs, as well as type 3, had a high risk of LNM. Additionally, four pathological risk factors associated with LNM were identified.

[Mixed Neuroendocrine-non-neuroendocrine Neoplasm of the Stomach that is Distributed in Depth on the Same Tumor: Inconsistent with the Definition of Mixed Adenoneuroendocrine Carcinoma in the 2010 World Health Organization Classification of Tumors of the Digestive System]

A mixed adenoneuroendocrine carcinoma (MANEC) of the stomach is a rare disease entity that was first defined by the World Health Organization (WHO) classification (2010) for tumors of the digestive system. According to the WHO classification (2010), MANEC is referred to as a tumor with both neuroendocrine and non-neuroendocrine neoplasms; each component of the tumor should be at least 30%. On the other hand, this cut-off value lacks clinical evidence and does not explain the characteristics and heterogeneity of this tumor. A 66-year-old male diagnosed with early gastric cancer (EGC) at a community hospital was referred to the Kosin University Gospel Hospital for further evaluation of gastric cancer. Esophagogastroduodenoscopy and EUS performed at the Kosin University Gospel Hospital revealed a sub-mucosal tumor-like component. In addition, a re-biopsy revealed a neuroendorine tumor at different depths of the same tumor. The final pathologic-diagnosis through surgery revealed a mixed neuroendocrine- non-neuroendocrine neoplasm, which is inconsistent with the definition of MANEC. Clinicians should consider EUS when a tumor has atypical endoscopic findings, even if EGC has already been diagnosed.

Gastric neuroendocrine tumor treated with endoscopic submucosal dissection

A case of a 59-year-old male patient with gastric neuroendocrine tumor which was misdiagnosed as adenocarcinoma, is presented. Herein, primary diagnosis was made due to the similarity of endoscopic pictures of both diseases and dues to the inappropriate interpretation of a small biopsy sample. The patient was qualified for endoscopic submucosal dissection. Microscopic examination of whole lesion, supplemented by immmunohistochemical reactions (chromogranin A, synaptophysin, cytokeratins 7 and 20, Ki67) revealed gastric neuroendocrine tumor (NET) G2.

The lesson learnt is that to provide effective treatment to the patient, it is necessary to use all available methods to make a proper diagnosis and to distinguish the suspected disease from others with similar features.