Exocrine Pancreatic Neoplasia - Dogs and Cats

Primary pancreatic tumours are rare, however the pancreas is also a site for metastasis from particularly gastro-intestinal neoplasms. Primary tumours include:

Carcinomas
Adenocarcinomas
Adenomas

It is important to make the distinction between pancreatic neoplasia and nodular hyperplasia which frequently occurs in older animals.

Signalment

Carcinomas:

Usually female dogs with a mean age of 10 years
Airedale terriers may have a breed predisposition
Affected cats have a mean age of 12 years

Description

Aetiology is idiopathic. Adenomas, although they do not metastasise and are frequently small and focal they can compress the surrounding pancreas. Carcinomas are aggressive with local invasion of the stomach or duodenum and metastasis to the liver, regional lymph nodes (hepatic and splenic), lungs, periotoneal surface and other abdominal organs. Other complications include blockage of the common bile duct and exocrine pancreatic insufficiency. Pancreatitis can also occur where pancreatic atrophy results in tumour necrosis and an inflammatory response.

Diagnosis

Clinical Signs

Non-specific including:

Lethargy
Weight loss
Anorexia
Vomiting
Diarrhoea
Constipation
Abdominal pain/distension
Jaundice - if biliary obstruction
Alopecia - as a paraneoplastic syndrome, ventral, facial and limbs in cats with adenocarcinoma

Physical Examination

In cats, a mass may be palpable in the abdomen

Haematology and Biochemistry

Potential abnormalities include:

Anaemia
Neutrophilia
Elevated hepatic enzymes or bilirubinaemia - if there is cholestasis or biliary obstruction
Hyperglycaemia - If there is concurrnet beta cell destruction
Hypokalaemia

Plain Radiography

Abdominal radiography may reveal a mass or mottled appearance on account of local peritonitis. In addition, there may be diplacement of the descending duodenum and pylorus. Where there is peritoneal metastasis and effusion loss of serosal detail and increased radiodensity may be observed. Thoracic radiography is also advised for pulmonary metastases.

Ultrasonography

Provides information on the extent of the tumour and its invasiveness. A guided fine needle aspirate may be taken at this time, however, cytological examination is often unrewarding as pancreatic tumour cells do not exfoliate well.

Exploratory Celiotomy

Excising the whole tumour if operable or taking a sample via shave biopsy or crush ligation allows histopathological confirmation.

Treatment

Surgery

Often at the time of diagnosis adenocarcinomas have already metastasised or local invasion has already taken place. If metastasis has no yet occurred surgical resection may be attempted with care to avoid iatrogenic trauma to the vascular supply to the proximal duodenum and obstruction of the main pancreatic duct. Total pancreatectomy is not advised. Tumours of the body or base of the pancreas are inoperable. Small pancreatic adenomas may be removed via partial pancreatectomy.

Chemotherapy

Not recommended.

Radiotherapy