[A Case of Type Ⅲ Gastric Neuroendocrine Tumor and Gastric Cancer Coexisting in the Same Lesion].

The patient is a 69-year-old male. He was referred from a nearby clinic for the evaluation of anemia. Upper gastrointestinal endoscopy revealed an ulcerative lesion corresponding to A1 in the gastric antrum. Biopsy pathology diagnosed adenocarcinoma(tub2>tub1). One month later, follow-up endoscopy showed that the macroscopic type of the ulcerative lesion had changed to type 1. Further examinations revealed no distant metastasis, leading to a diagnosis of advanced gastric cancer. Consequently, laparoscopic distal gastrectomy was performed. Postoperative pathological examination confirmed the coexistence of undifferentiated carcinoma and neuroendocrine tumor(NET)(G3)within the same lesion. Gastric NETs are classified into 3 types by Rindi et al., based on background factors. This case was diagnosed as Type Ⅲ, as it did not involve type A gastritis, Zollinger-Ellison syndrome, or multiple endocrine neoplasia type 1(MEN1). Type Ⅲ typically presents as a solitary lesion with higher malignancy. Cases of Type Ⅲ gastric NETs coexisting with carcinoma within the same lesion are extremely rare.