Ampullary Carcinoma

Published on 18/07/2015 by admin

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Last modified 18/07/2015

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 Well defined/lobulated or poorly marginated

image Almost always obstructs common bile duct (CBD)
image Pancreatic duct (PD) obstructed in only ∼ 50%, and usually does not cause upstream pancreatic atrophy
image 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+

image 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

image Tumors arising from duodenal epithelium (intestinal type): Prognosis comparable to duodenal carcinoma
image Tumors arising from pancreaticobiliary epithelium of distal CBD/PD (pancreaticobiliary type): Worst prognosis, with outcomes similar to pancreatic adenocarcinoma
image 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
image
(Left) Graphic shows ampullary carcinoma image causing obstruction of both the common bile duct (CBD) image and the pancreatic duct (PD) image.

image
(Right) ERCP in a patient with a history of familial polyposis shows a small mass image 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.
image
(Left) Coronal CECT demonstrates a classic double-duct sign caused by an ampullary carcinoma image, with obstruction of both the common bile duct image and pancreatic duct image. Note the abrupt occlusion of both ducts by the mass.

image
(Right) Coronal CECT demonstrates a lobulated mass image 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

image Soft tissue mass centered in ampulla
image Double duct sign with obstruction of both common bile duct (CBD) and pancreatic duct (PD)
• Location

image Centered in region of ampulla of Vater or overlying periampullary duodenal mucosa
• Size

image 1-4 cm in diameter; mean 2.7 cm
• Morphology

image 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

image Can be well defined/lobulated or poorly marginated/infiltrative
image Almost always obstructs CBD with abrupt cut-off of CBD by mass
image 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)

image Secondary signs suggest presence of tumor (e.g., double-duct sign, irregular obstructed duct, etc.)
• Most common sites of metastases: Lymph nodes or liver

MR Findings

• Typically low signal on T1WI, intermediate to high signal on T2WI, and hypoenhancing relative to pancreas on T1WI C+
• CBD ± PD dilatation with abrupt ductal cutoff

image MRCP: Abrupt, irregular cut-off of distal CBD
• Diffusion-weighted images may increase sensitivity for small masses (malignant ampullary tumors have lower ADC values than benign lesions)

Ultrasonographic Findings

• Grayscale ultrasound

image May be useful as initial screening tool for detection of biliary dilation in patients presenting with jaundice
image Distal CBD and PD can be difficult to visualize as a result of bowel gas

– Ampullary mass almost never visible on US
image Liver metastases in advanced cases
• Endoscopic US

image Tumors usually visible endoscopically, but endoscopic US may help guide biopsy and improve biopsy yields
image Best modality for T staging (accuracy up to 90%)
image May help detect and biopsy nodal metastases

Radiographic Findings

• ERCP

image Ampullary mass should be readily visible under endoscopy in most cases and can be easily biopsied

– Superior to CT in detecting small tumors
image Cholangiography demonstrates obstruction of CBD and PD with abrupt cut-off at mass

Fluoroscopic Findings

• Upper GI series: Filling defect in 2nd portion of duodenum in region of ampulla of Vater

image No specific features to differentiate ampullary tumor from pancreatic or duodenal malignancy

Angiographic Findings

• Conventional

image Superselective injection of gastroduodenal artery demonstrates hypovascular mass

Nuclear Medicine Findings

• PET

image May demonstrate liver metastases as FDG-avid lesions
• Hepatobiliary scintigraphy

image Dilated bile ducts

Imaging Recommendations

• Best imaging tool

image CECT with dedicated biphasic pancreatic protocol or MR with MRCP
• Protocol advice

image Patients drink 500 cc water immediately prior to CT to distend duodenum (improving visualization of ampulla)
image Dual-phase acquisition (arterial and venous phases) critical for improving visualization of tumor

– Lesions may be more or less conspicuous on each phase
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