Brunner's gland metaplasia of residual jejunum developed long after wide resection of the small intestine

We report a rare case in which mucous glands, similar to pyloric or Brunner's glands, developed in the residual jejunum (46 cm in length) long after wide resection of the small intestine. The mucous glands were observed in the mucosal and submucosal layers near the duodenum, and the mucin showed a positive reaction by paradoxical concanavalin A staining and immunoreactivity for HIK-1083, which were histochemically the same as those in the pyloric/Brunner's glands. This type of metaplasia in the small intestine without ulceration has not been described in the literature so far. It was speculated that these glands developed as a defense response or adaptation against relatively excessive acid due to the short small intestine.