Pancreatic Duct Stricture

Pancreatic duct stricture is focal narrowing of the main pancreatic duct with upstream dilatation. It is benign in most cases of chronic pancreatitis but must be separated from pancreatic cancer.

Benign strictures occur in about 20% to 30% of chronic pancreatitis. Other causes are acute necrotising pancreatitis, trauma, surgery, autoimmune pancreatitis and intraductal papillary mucinous neoplasm.

Pathophysiology.

Fibrosis around the duct, or compression by a pseudocyst or inflamed gland, raises intraductal pressure. This produces pain, recurrent pancreatitis and atrophy of the gland upstream.

Pain after meals, recurrent acute pancreatitis, steatorrhoea, weight loss, diabetes and, in head strictures, jaundice.

Red flags.

• Weight loss with new onset diabetes (cancer).
• Jaundice with a stricture.
• Recurrent pancreatitis with fever.

Magnetic resonance cholangiopancreatography with secretin shows the stricture, upstream dilatation and stones. Endoscopic ultrasound with fine needle biopsy, and CT, exclude a mass. Measure CA 19-9 and IgG4. Pancreatoscopy with biopsy or brushings is used for indeterminate strictures. Faecal elastase assesses exocrine function.

Differential diagnosis.

• Pancreatic ductal adenocarcinoma.
• Autoimmune pancreatitis.
• Intraductal papillary mucinous neoplasm.
• Duct stones.
• Pancreas divisum.

Rule out malignancy first. Endoscopic stenting is the first treatment for a dominant stricture in the head with symptoms: place a single plastic stent (10 French) and exchange it every 3 months for 12 months, or use multiple plastic stents or a fully covered metal stent, with the duct reassessed after removal. Surgery (drainage procedures or resection) is used when stenting fails or the stricture recurs.

• Indomethacin (prophylaxis of post-procedure pancreatitis): 100 mg rectally once, immediately before or after the procedure; maximum 100 mg; monitor renal function and bleeding; avoid in peptic ulcer, renal impairment and non-steroidal drug allergy.
• Pancrelipase (exocrine insufficiency): 40,000 to 50,000 lipase units with each main meal and 20,000 to 25,000 with snacks; maximum 10,000 lipase units/kg daily; monitor weight and stool; reduce if the maximum is reached without benefit and re-check the diagnosis.
• Paracetamol: 1 g orally every 6 hours; maximum 4 g daily (3 g daily if weight under 50 kg or with liver disease); monitor liver tests.

Treat autoimmune pancreatitis with prednisolone when the diagnosis is confirmed.

Monitoring. Symptoms and weight at each stent exchange; imaging yearly after stent removal.

Referral and escalation. Pancreatic endoscopy and surgery.