Types of Ampulla of Vater
The ampulla of Vater is classified histologically into two main types based on the epithelial origin: pancreatobiliary type and intestinal type, which arise from the biliary epithelium or small bowel epithelium, respectively. 1
Histological Classification
The ampulla of Vater represents the junction where the pancreatic and distal common bile ducts converge, and cancers arising from this location demonstrate distinct histological patterns:
Pancreatobiliary type: Arises from the biliary epithelium and exhibits characteristics similar to cholangiocarcinoma or pancreatic ductal adenocarcinoma 1
Intestinal type: Originates from the small bowel epithelium lining the ampulla and demonstrates features similar to duodenal or colorectal adenocarcinoma 1
Clinical Significance of Classification
The histological subtype has important prognostic and therapeutic implications, as these cancers follow distinct clinical courses and management approaches compared to other biliary tract cancers. 1
The American College of Surgeons recognizes intra-ampullary papillary tubular neoplasms as mucinous neoplasms growing within the ampulla, which can progress from benign to malignant along an adenoma-carcinoma sequence 2
These ampullary tumors are sometimes grouped under biliary tract cancers in chemotherapy studies due to their rarity, though they warrant separate consideration 1
Anatomical Context
The ampulla of Vater is located at the major duodenal papilla in the second portion of the duodenum, where the dilated junction of the bile and pancreatic ducts enters 3
The ampulla is surrounded by the sphincter of Oddi, which controls bile and pancreatic juice flow while preventing reflux 3
Endoscopic examination may reveal ampullary tumors as large exophytic growths, ulcerated lesions, or masses behind the papillary orifice covered by normal mucosa 4
Associated Neoplastic Conditions
Patients with familial adenomatous polyposis (FAP) have significantly increased risk of periampullary cancers, including ampullary adenomas and carcinomas. 1
The median interval between colectomy for FAP and development of upper gastrointestinal cancer is 22 years 1
Duodenoscopy surveillance should begin when colorectal polyps are diagnosed, with intervals based on polyposis stage (5 years for stage 0/1,3 years for stage 2,1-2 years for stage 3) 1
Stage 4 duodenal polyposis warrants surgical resection by pylorus-preserving pancreaticoduodenectomy 1
Diagnostic Considerations
Biopsy of the major duodenal papilla can provide valuable diagnostic information, particularly when evaluating for IgG4-related sclerosing cholangitis, with sensitivity of 52% and specificity of 89% using a threshold of 10 IgG4-positive cells per high power field 1
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