A solitary Peutz-Jeghers-type polyp in the duodenum is rare. Here, we report about a 65-year-old man with diabetes mellitus and hypertension. Screening with upper gastrointestinal endoscopy revealed a pedunculated polyp in the duodenal second portion. Endoscopic biopsies revealed a hyperplastic polyp. The polyp had an irregular nodular and lobular surface and was increasing in size over time. Therefore, endoscopic resection was performed. Histopathological examination of the polyp revealed smooth muscle bundles from the muscularis mucosae extending to the polyp, forming a typical branch-like structure. The present case was diagnosed as a Peutz-Jeghers-type polyp of the duodenum. Its histopathological features were identical to those of Peutz-Jeghers polyp; however, the clinical features of Peutz-Jeghers syndrome, such as mucocutaneous pigmentation and family history of the disease, were absent.
