Inverted cystic tubulovillous adenoma involving Brunner's glands of duodenum

Abstract

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.

Figure 1

A: Gastroduodenoscopic examination and polypectomy. 1.1 cm sized, centrally depressed, sessile tumor was seen in the contralateral portion to the ampulla of Vater; B: After submucosal injection with a mixture of saline, epineprine and indigocarmine, snare polypectomy was successfully performed.

Figure 2

A: Inverted cystic lesion extends along the Brunner gland duct into the submucosa (HE, × 15); B: Normal or hyperplastic Brunner’s glands (arrows) are seen beneath the tubulovillous adenomatous lesion growing into the cyst lumen (HE, × 40); C: The flat surface epithelium and small mucus glands (arrows) are seen among the villiform epithelium (HE, × 40).

Figure 3

A: PAS staining shows positive reaction in the cytoplasm of normal Brunner’s glands (arrow) and tubulovillous glands (PAS, × 40); B: The duodenal surface epithelium is positive for CD10 along the luminal border (arrow), but the Brunner’s glands and adenomatous lesion are negative (Immunohistochemistry CD10, × 40); C: The immunohistochemical stain for MUC2 shows focal positive staining in duodenal mucosa and tubulvillous lesion, but not in Brunner’s glands (arrow) (Immunohistochemistry MUC2, × 40); D: whereas the staining for MUC5AC shows negative staining in duodenal mucosa and Brunner’s glands (arrow), but partly positive in adenomatous lesion (Immunohistochemistry MUC5AC, × 40); E: The area corresponding to the Figure 2B was negative for MUC2 in surface and glandular epithelium (arrows) (Immunohistochemistry MUC2, × 40); F: but positive for MUC5AC (arrows) (Immunohistochemistry MUC5AC, × 40).