Gastric Neuroendocrine Carcinoma with Rapid Progression

As gastric neuroendocrine carcinoma (NEC) is a rapidly growing cancer, most cases are diagnosed at advanced stages. We herein report a 74-year-old woman with an early-stage gastric NEC whose history included endoscopic submucosal dissection treatment for three early-stage gastric cancer lesions five years prior to the current presentation. We also describe the changes observed over time. An endoscopic examination during follow-up revealed an NEC (measuring 6 mm) in the gastric vestibule, for which distal gastrectomy was performed. Four months before surgery, the carcinoma exhibited specific morphological changes and lymphovascular invasion (despite the tumor being stage 1), suggesting a high-grade NEC.