Ampullary adenocarcinoma
Ampullary adenocarcinomas are rare biliary tumors arising from the distal biliary epithelium at the ampulla of Vater.
Although classically presenting on imaging with the double duct sign, the tumor itself may be occult or of limited characterization imaging.
Epidemiology
These are rare tumors, with an adulthood estimated incidence of 0.70 cases out of 100.000 men and 0.45 cases out of 100.000 women in the United States .
Clinical presentation
These patients typically present with obstructive jaundice and abdominal pain, but presentation may be vague with other nonspecific symptoms.
Radiographic features
US, CT, and MRI all demonstrate the double duct sign: simultaneous dilatation of the common bile and pancreatic ducts; seen in ~52% of cases .
CT
- may demonstrate a solid enhancing small tumor in the ampullary region protruding into the second portion of the duodenum
- lobulated or infiltrative margins have been described
- discrete tumors may not be visible
- CT IV Cholangiogram it is usually not performed given biliary obstruction and raised bilirubin levels
MRI
MRCP has been described as more sensitive than other imaging modalities for depicting ampullary lesions, but with low specificity though .
- T2
- it may delineate the presence of an ampullary mass or papillary bulging
- besides the biliary tree dilatation, may show irregular narrowing of the distal common bile duct
- DWI/ADC: some degree of restricted diffusion help in differentiating from benign lesions
Treatment and prognosis
Tumors that are occult on imaging are also frequently occult at ERCP/endoscopy, with the diagnosis only achieved after papillotomy/biopsy .
Differential diagnosis
- ampullary adenoma
- papillitis
- papillary stenosis (e.g. post-inflammatory)
