ENDOSCOPIC DIAGNOSIS OF GASTRIC NEUROENDOCRINE TUMOR AND NEUROENDOCRINE CARCINOMA

Abstract

Gastric neuroendocrine tumor (G-NET) is a tumor with low malignancy and good prognosis. Gastric neuroendocrine carcinoma (G-NEC), a rare subtype of gastric cancer (0.2-0.6% of all gastric cancers), is characterized by rapid growth, frequent lymphovascular invasion, and a high metastasis rate, with aggressive biological behavior. Most G-NEC cases are diagnosed at advanced stages with lymph node or distant metastases, and the prognosis of G-NEC is worse than that of common-type gastric adenocarcinomas. Thus, G-NETs and G-NECs have completely different characteristics and should be differentiated endoscopically. In white-light endoscopy, G-NET presented as elevated lesions, with “reddish color,” “dilated vessels,” “SMT-like marginal elevation,” and “central depression.” G-NEC showed as depressed or ulcerative lesions, with “SMT-like marginal elevation,” “adherent white coat,” and “ulceration with a distinct border.” On magnifying narrow-band imaging, “absent microsurface (MS) pattern plus irregular microvascular (MV) pattern” in the central depression and “absent MS pattern plus disrupted irregular MV” were characteristic findings of G-NET and G-NEC, respectively. These endoscopic features should be considered to increase the index of suspicion and correctly diagnose G-NETs and G-NECs through the pathological examination of biopsy specimens.