Ampullary carcinoma often presents with the classic clinical triad of abdominal pain, jaundice, and weight loss and an enhancing mass at the ampulla of Vater.
Description
Ampullary carcinoma is a malignant tumour that arises from the ampulla of Vater, which is an anatomical complex that encompasses the distal common bile duct, the main pancreatic duct, and the duodenal papilla. Ampullary carcinomas represent approximately 0.2% of gastrointestinal malignancies and are the second most common periampullary malignancy after pancreatic cancer.
Pathogenesis
The pathogenesis of ampullary carcinoma is not fully understood, but it is thought to involve a sequence of progressive genetic mutations. Key mutations include those in TP53, KRAS, APC, and SMAD4 genes, which are involved in cellular growth and apoptosis. These mutations can lead to unchecked cell proliferation and eventual tumour formation.
Subtypes
There are two main histologic subtypes: intestinal type and pancreatobiliary type. The intestinal type is more common and usually carries a better prognosis.
Epidemiology, Risk Factors & Associations
- Most common in older adults (median age at diagnosis: 60-70 years).
- Slightly more common in men than women.
- Associated with conditions that increase the risk of gastrointestinal cancers, such as familial adenomatous polyposis (FAP).
Clinical Features
- Classic triad of abdominal pain, jaundice, and weight loss.
- Steatorrhoea and dark urine due to obstruction of the biliary tree.
Complications
- High risk of malignant progression and metastasis, particularly to the liver, peritoneum, and lungs.
- Local invasion can lead to obstruction of the bile and pancreatic ducts, causing obstructive jaundice and pancreatitis.
Pathological Features
Histopathology
- Macroscopic: Usually a firm, white-yellow mass located at the ampulla.
- Microscopic: Characterised by glandular or ductal structures with varying degrees of cellular atypia and invasion.
Serology
No specific serological markers for ampullary carcinoma.
Biochemistry
- Elevated bilirubin and alkaline phosphatase due to biliary obstruction.
Radiological Features
General Features
- An enhancing mass at the ampulla of Vater.
- Dilatation of the common bile duct and pancreatic duct upstream from the tumour.
CT
- Non-contrast: Hypodense mass at the ampulla.
- Contrast-enhanced: The tumour enhances during the arterial phase and washes out in the portal venous phase.
MRI
- T1WI: Hypointense mass.
- T2WI: Hyperintense mass.
- T1 C+: Enhancing mass.
- DWI/ADC: Restricted diffusion can be seen due to high cellularity of the tumour.
US
- B-mode: Hypoechoic mass at the ampulla.
- Colour Doppler: May demonstrate vascularity within the tumour.
NM
- PET FDG: Hypermetabolic mass at the ampulla, can help in detecting distant metastases.
Grading and Staging
The tumour is staged according to the TNM system, taking into account the size and extent of the tumour (T), involvement of local lymph nodes (N), and the presence of distant metastasis (M).
Diagnosis
Diagnosis is confirmed by endoscopic biopsy and histopathological examination.
Differential Diagnosis
- Pancreatic carcinoma: More common than ampullary carcinoma and usually presents with similar symptoms. However, pancreatic tumours often cause a more pronounced dilatation of the pancreatic duct than ampullary tumours.
- Cholangiocarcinoma: May also present with obstructive jaundice and a biliary mass, but is usually located more proximally in the bile ducts.
Management
Surgical resection, usually in the form of a pancreaticoduodenectomy (Whipple procedure), is the treatment of choice. Adjuvant chemotherapy or radiotherapy may be offered depending on the stage of the disease.