A case of early gastric cancer in a patient with gastric juvenile polyposis diagnosed by magnifying endoscopy and resected by endoscopic submucosal dissection.

Gastric juvenile polyposis (GJP) is frequently associated with the development of gastric cancer. However, there are no reports of gastric cancer in patients with GJP diagnosed using magnifying endoscopy with narrow-band imaging (M-NBI) and successfully treated by endoscopic submucosal dissection (ESD). A 50-year-old woman was referred to our hospital. Conventional white-light endoscopy revealed numerous aggregated polyps with reddish and whitish areas in the gastric cardia. M-NBI revealed a regular microvascular pattern (MVP) and regular microsurface pattern (MSP) in the reddish area of the lesion, and they were diagnosed as non-cancerous polyps. There was a clear demarcation line between the reddish and whitish areas, with irregular MVP plus irregular MSP in the whitish area, which was diagnosed as early gastric cancer. The horizontal extent of the cancer was precisely identified using M-NBI, and the en bloc resection of cancerous lesions was performed using ESD. Histopathological examination of the resected specimen showed that the reddish area comprised a hyperplastic foveolar epithelium. Conversely, the whitish area was diagnosed as a well-differentiated adenocarcinoma. The cancer was limited to the mucosa, lymphovascular invasion was negative, and horizontal and vertical margins were free from cancerous tissue. According to surveillance endoscopy, there has been no recurrence 11 years after ESD. This is the first report demonstrating that M-NBI is useful for making a precise diagnosis of cancer in juvenile polyposis and that ESD can be an option for the treatment of such a cancer.