A case of early gastric cancer accompanied by a hamartomatous inverted polyp and successfully managed with endoscopic submucosal dissection.

during a regular health check−up in a 59− year−old man. Following barium meal study the SMT was shown to be growing. He visited our hospital for further exami− nation. The upper gastrointestinal endoscopy re− vealed an SMT in the posterior wall of the upper third area of the stomach, with bridging fold and positive cushion sign (l" Figure 1). A focal discoloration of mu− cosa at the top of the SMT indicated the possibility of co−existence of gastric can− cer. We therefore performed a biopsy of this mucosa, and irregular tubular struc− tures were observed on pathologic stud− ies. No malignancy was observed in the mucosa around the SMT. Endoscopic sub− mucosal dissection was carried out for di− agnostic therapy. Pathologic examinations revealed irregu− lar tubular structures limited to the mu− cosal layer, and an immunohistochemical test revealed p53−positive staining (l" Figure 2). In the submucosal layer, cystic dilated glands without atypia were observed, compatible with hamartoma− tous inverted polyp (HIP). These facts in− dicated early gastric cancer (IIb) on the surface of the HIP. HIP is characterized pathologically as a proliferation of cystic dilated glands without atypia, accompanied by dendri− tic proliferation of the smooth muscle bundle [1]. HIP is very rare and difficult to diagnose. In addition, HIP is reported as a paracancerous lesion, and is associat− ed with gastric cancers [1,2]. Therefore, we have to diagnose it immediately and carefully with these points in mind dur− ing endoscopic studies, including biopsy. However, a superficial biopsy cannot be effective for critical diagnosis of submu− cosal lesions. We propose that aggressive biopsy of SMT is necessary if equivocal findings are noted. Endoscopic submucosal dissection can be an effective procedure of diagnos− tic therapy for HIP and early cancer. Thus, HIP can be one of the differential diagno− ses of SMT lesions of the stomach, and can be occasionally associated with early gastric cancer.