Benign neoplasia of the duodenum are very rare. Moreover, duodenal tubulovillous adenomas are more uncommon lesions. The microscopic structure of tubulovillous adenoma has frond-like projection of mucosa with branching papillary structure and generally upward growth into the lumen. We describe a 72-year-old man who showed aduodenal tubulovillous adenoma with unusual inverted cystic growth pattern. Interestingly, this tubulovillous adenomatous lesion was interrupted by gastric metaplasia in the deep portion of the cyst and was closely surrounded by Brunner's glands. Although histogenesis of gastric metaplasia of duodenum is not fully understood, Brunner's glands has been suggested as a precursor for gastric metaplasia. Therefore, these findings argued that this adenoma arises from Brunner's glands through gastric metaplasia. This is the first case of inverted cystic tubulovillous adenoma involving Brunner's glands of duodenum with gastric metaplasia.

The pathological expressions of Brunners gland hyperplasia into adenoma and hamartoma.Saudi Med J. 2003 Nov;24(11):1256-60.

The terms Brunners gland adenoma and hamartoma are 2 pathological expressions of hyperplasia of these glands. We report 3 patients and review the recent literature to support our hypothesis of common pathology. Awareness of the existence and character of Brunners gland lesions will increase the possibility of their accurate diagnosis.

Hemoclip-assisted polypectomy of large duodenal Brunner's gland hamartoma.Dig Dis Sci. 2006 Sep;51(9):1670-2. Epub 2006 Aug 22.

Brunner's gland hamartoma, also known as Brunneroma or Brunner's gland adenoma, is a rare tumor of the duodenum and an uncommon cause of gastrointestinal bleeding. In symptomatic patients, treatment requires either surgical resection or endoscopic polypectomy. We report a case of upper gastrointestinal bleeding from a pedunculated Brunner's gland hamartoma in the duodenal bulb. A new technique using hemoclip-assisted polypectomy is described to remove a large pedunculated Brunner's gland hamartoma.