A case of giant gastric hyperplastic polyp developing after endoscopic mucosectomy for early gastric cancer

We report a patient with giant Yamada (Y)-3 type gastric hyperplastic polyp developing after endoscopic mucosectomy for early gastric cancer. Sixty two year old man was admitted to our hospital due to endoscopic mucosectomy for early gastric cancer (type IIc+IIa) in the antrum. The removed lesion revealed histologically as well differentiated tubullar adenocarcinoma confined to the mucosa. Follow-up endoscopy about 10 months after mucosectomy showed a polypoid lesion in the resected site, which was identified histologically hyperplastic polyp. The polyp had grown up to Y-3 type, sized about 25mm in diameter, so it was resected by endoscopic polypectomy. A case of gastric hyperplastic polyp developing after endoscopic mucosectomy for early gastric cancer has been rarely reported in Japan. The mechanism was still unknown, but was thought that excessive regeneration of epithelium was promoted by formation of ulcer after endoscopic mucosectomy, administration of H₂-receptor antagonist and mechanical stimulation by increased peristalsis.