Two Cases of Primary Gastric Mixed Neuroendocrine-non-neuroendocrine Neoplasm

Abstract

The 2019 WHO classification defines mixed neuroendocrine-non-neuroendocrine neoplasm (MiNEN) as a combination of non-neuroendocrine and neuroendocrine components, with each accounting for more than 30%. Two cases of gastric MiNEN are reported. Case 1 was a 75-year-old man with a preoperative diagnosis of gastric cancer on the posterior wall of the antrum and multiple liver metastases who underwent palliative distal gastrectomy. The pathological diagnosis was MiNEN (adenocarcinoma : 70%, endocrine carcinoma : 30%), pT4a (SE), pNX, M1 (HEP), pStage IV. The patient refused chemotherapy after surgery and died of the original disease 3 months after surgery. Case 2 was a 75-year-old man who was diagnosed with gastric cancer on the antrum-greater curvature and underwent distal gastrectomy. The pathological diagnosis was MiNEN (adenocarcinoma : 40%, endocrine carcinoma : 60%), pT4a (SE), pN1 (#6), M0, pStage IIIA. Peritoneal dissemination was observed 18 months after surgery, but the patient declined aggressive treatment and died of the original disease 21 months after surgery.