Superficial non-ampullary duodenal cancer identified by small-bowel capsule endoscopy: a case report (with video).

Herein, we report for the first time a case of a surficial superficial non-ampullary duodenal cancer causing obscure intestinal bleeding that was identified by small-bowel capsule endoscopy and treated by endoscopic mucosal resection. A 73-year-old man underwent upper gastrointestinal endoscopy to identify the cause of anemia. Although conventional duodenoscopy revealed a flat, elevated 5-mm lesion with a central recess and "milk-white mucosa" at the inferior duodenal angulus, capsule endoscopy revealed a white nodular 5-mm lesion with central recess at the duodenum slightly to the anal side from the major duodenal papilla. Pathohistological examination revealed a low-grade well-differentiated tubular adenocarcinoma growing locally in the mucosal layer. Although capsule endoscopy detected a nodular lesion, conventional endoscopy revealed a flat, elevated lesion. The cause of this difference in endoscopic findings is considered to be the degree of extension of the intestinal mucosa. In contrast, "milk-white mucosa" as a typical finding of superficial duodenal tumor in conventional endoscopy could be identified as a white mucosal color tone in capsule endoscopy. Conventional endoscopic findings of irregular surface structure in the lesion suggested malignancy. Pathohistologically, the ductal structure of the adenocarcinoma was also distorted. Unfortunately, it was difficult to suggest that the lesion was adenocarcinoma based on the endoscopic findings alone.