Ampulla of Vater

The ampulla of Vater, also hepatopancreatic ampulla, is found in the duodenum. It has a unique histology and is a relatively common site of disease, when duodenal pathology is considered.

Normal histology

Periampullary:

• Intestinal epithelium with goblet cells.

Papilla of Vater (the projection into the duodenal lumen):

• Goblet cells in foveolar-like epithelium.

Note about heterotopias:

• +/-Pancreatic heterotopia - common.
• +/-Gastric heterotopia - not common.

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DUODENAL BULB, BIOPSY:
- GASTRIC HETEROTOPIA.
- NEGATIVE FOR MALIGNANCY.

Ampullary tumours

• AKA tumours of the ampulla of Vater.
• AKA tumours of the hepatopancreatic ampulla.

Ampullary adenoma

General

• Uncommon.
• May be associated with familial adenomatous polyposis (FAP).

Microscopic

Features:

• +/-Paneth cells - may be prominent.
• Similar to adenoma of colon - with:
  • Less pseudostratification.
  • Finer chromatin pattern.

DDx:

• Ampullary carcinoma.
• Duodenal carcinoma secondarily involving the ampulla.
• Pancreatic adenocarcinoma secondarily involving the ampulla.

Images

www:

• Ampullary adenoma (ajcpjournals.org).
• Ampullary adenoma - pitfalls (ajcpjournals.org).

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See tubular adenoma.

Ampullary carcinoma

• AKA ampullary adenocarcinoma.

General

• Uncommon.
• Textbook association: familial adenomatous polyposis.
• Prognosis guarded but significantly better than pancreatic ductal adenocarcinoma - 5 year survival ~40% for ampullary carcinomas vs. 10% for pancreatic adenocarcinoma.

Gross

• Ampullary carcinomas are classified by site.
• Modest differences exist in survival between the sites.

Classification

Adsay et al. proposed a four subtype classification system:

Subtype	Prevalence	Origin/definition	Notes
Intra-ampullary papillary-tubular carcinoma	~25% of cases	arises from intra-ampullary epithelium and/or distal end of CBD or pancreatic duct	generalized category intra-ampullary papillary-tubular neoplasm -- the ampullary counterpart of the IPMN of the pancreas
Ampullary-ductal carcinoma	~15% of cases	arises from intra-ampullary ducts
Peri-ampullary duodenal carcinoma	~5% of cases	primarily in the duodenum; ampullary orfice must be clearly within lesion
Ampullary carcinoma not otherwise specified	~55% of cases	arise from papillary projection into duodenum - from foveolar-like epithelium with goblet cells

Microscopic

Dependent on histologic subtype:

1. Intestinal ampullary carcinoma.
2. Pancreaticobiliary ampullary carcinoma.
3. Other.

Notes:

• May lack desmoplastic stroma.

DDx:

• Invasive ductal carcinoma of the pancreas - has a much worse prognosis.
• Ectopic pancreas.
• Duodenal adenocarcinoma with secondary involvement of the ampulla.

Intestinal ampullary carcinoma

Features:

• Pseudostratified columnar epithelium with hyperchromatic, ellipsoid nuclei.
  • Glands usually tightly packed, i.e. high gland-to-stroma ratio; often >2:1.

Note:

• Similar to colorectal adenocarcinoma.

Pancreatobiliary ampullary carcinoma

Features:

• Tubular arrangements consisting of cuboidal cells in one or two layers.
  • Tubules usually spaced; ~1:3 gland-to-stroma ratio.

Images

• 

  PA - low mag. (WC)

• 

  PA - intermed. mag. (WC)

• 

  PA - high mag. (WC)

• 

  PA - high mag. (WC)

Other

Features - any of the following characteristics:

• Non-tubular morphology/poorly-differentiated.
• Micropapillary architecture.
• Medullary.
• Signet ring cells.
• Mucin:
  1. Colloid.
  2. Mixed-mucinous.
  3. Mucinous-signet-ring.

IHC

Features:

• CK7 +ve.
• CK20 +ve.
• MUC2 +ve.

Others:

• SMAD4 +ve/-ve.
  • Lost in pancreatic neoplasia ~90% of cases vs. ~35% of ampullary tumours.
• p53 +ve ~55% of cases.
• E-cadherin +ve ~40% of cases.
• Beta-catenin +ve ~65% of cases.

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• Separate CAP protocol.

See also

• Duodenum.
• Small bowel.
• Gastrointestinal pathology.