Pancreatic duct (PD) obstructed in only ∼ 50%, and usually does not cause upstream pancreatic atrophy
Small masses often not visualized on CT
– Secondary signs should suggest presence of tumor (e.g., double duct sign, etc.)
• MR: Low signal on T1WI, intermediate signal on T2WI, and hypoenhancing on T1WI C+
Diffusion-weighted images may increase sensitivity for small masses
TOP DIFFERENTIAL DIAGNOSES
• Pancreatic head adenocarcinoma involving ampulla
• Ampullary adenoma
• Distal CBD cholangiocarcinoma
• Periampullary duodenal carcinoma
• Ampullary carcinoid tumor
PATHOLOGY
• Markedly increased incidence in hereditary polyposis syndromes
• Lesions can be divided into 3 forms
Tumors arising from duodenal epithelium (intestinal type): Prognosis comparable to duodenal carcinoma
Tumors arising from pancreaticobiliary epithelium of distal CBD/PD (pancreaticobiliary type): Worst prognosis, with outcomes similar to pancreatic adenocarcinoma
Intraampullary tumors: Best prognosis with early ductal obstruction and consequent early presentation
CLINICAL ISSUES
• Obstructive jaundice (80%) most common symptom
• Same surgical treatment (Whipple procedure) as for all periampullary neoplasms
(Left) Graphic shows ampullary carcinoma causing obstruction of both the common bile duct (CBD) and the pancreatic duct (PD) .
(Right) ERCP in a patient with a history of familial polyposis shows a small mass causing obstruction of the distal common duct at the ampulla. Patients with familial polyposis have a substantially increased risk of developing ampullary (and other) carcinomas. Lifelong surveillance is required to detect bowel, stomach, and biliary tumors.
(Left) Coronal CECT demonstrates a classic double-duct sign caused by an ampullary carcinoma , with obstruction of both the common bile duct and pancreatic duct . Note the abrupt occlusion of both ducts by the mass.
(Right) Coronal CECT demonstrates a lobulated mass centered at the ampulla obstructing the pancreatic and common bile ducts. While this was a pancreaticobiliary type lesion at histology, individual subtypes of ampullary carcinoma cannot be distinguished on imaging.
TERMINOLOGY
Definitions
• Heterogeneous group of malignant epithelial neoplasms (adenocarcinoma) arising from ampulla of Vater
IMAGING
General Features
• Best diagnostic clue
Soft tissue mass centered in ampulla
Double duct sign with obstruction of both common bile duct (CBD) and pancreatic duct (PD)
• Location
Centered in region of ampulla of Vater or overlying periampullary duodenal mucosa
• Size
1-4 cm in diameter; mean 2.7 cm
• Morphology
Can be either well-defined lobulated mass or more infiltrative and ill defined
CT Findings
• Mass with variable attenuation (most often hypodense) centered in ampulla
Can be well defined/lobulated or poorly marginated/infiltrative
Almost always obstructs CBD with abrupt cut-off of CBD by mass
PD obstructed in only ∼ 50% of cases, with ampullary tumors much less likely than pancreatic cancer to cause upstream pancreatic atrophy
• Small masses may not be visualized on CT (or any other radiological imaging modality)
Pancreatic duct (PD) obstructed in only ∼ 50%, and usually does not cause upstream pancreatic atrophy
Tumors arising from duodenal epithelium (intestinal type): Prognosis comparable to duodenal carcinoma
causing obstruction of both the common bile duct (CBD) 
and the pancreatic duct (PD) 
.
causing obstruction of the distal common duct at the ampulla. Patients with familial polyposis have a substantially increased risk of developing ampullary (and other) carcinomas. Lifelong surveillance is required to detect bowel, stomach, and biliary tumors.
, with obstruction of both the common bile duct 
and pancreatic duct 
. Note the abrupt occlusion of both ducts by the mass.
centered at the ampulla obstructing the pancreatic and common bile ducts. While this was a pancreaticobiliary type lesion at histology, individual subtypes of ampullary carcinoma cannot be distinguished on imaging.
Patients drink 500 cc water immediately prior to CT to distend duodenum (improving visualization of ampulla)
