Pancreatic Duct Stones

Pancreatic duct stones are calcified concretions in the main pancreatic duct or its branches, found in 30% to 60% of patients with chronic pancreatitis. They obstruct the duct and drive pain and recurrent pancreatitis.

They are composed of calcium carbonate with a protein matrix. Alcohol is the commonest cause, and hereditary, tropical, hypercalcaemic and idiopathic forms also occur.

Pathophysiology.

Reduced secretion of the protective protein lithostathine and increased calcium carbonate saturation make protein plugs that calcify. Obstruction raises pressure in the duct and causes ischaemia and pain.

Epigastric pain radiating to the back, often after meals, recurrent pancreatitis, steatorrhoea, weight loss and diabetes.

Red flags.

• Jaundice or cholangitis from a head stone.
• Weight loss with a stricture (cancer).
• Pseudocyst formation.

Plain radiograph, ultrasound and CT show calcification in the duct. Magnetic resonance cholangiopancreatography shows duct size, stones and strictures. Endoscopic ultrasound shows small stones and parenchymal change. Faecal elastase assesses exocrine failure.

Differential diagnosis.

• Parenchymal calcification without duct stones.
• Pancreatic cancer with calcification.
• Duct stricture.
• Gallstone disease.

Treat stones over 5 mm with extracorporeal shock wave lithotripsy, then endoscopic extraction by basket or balloon. Stones under 5 mm in a non-obstructed duct are treated by endoscopic extraction alone. Stent downstream strictures. Surgery (lateral pancreaticojejunostomy, or resection for head mass) is used for failed endoscopic treatment.

• 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: 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.
• 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.

Stop alcohol and tobacco.

Monitoring. Pain, weight and imaging at 3 months, then yearly; vitamin D and fat soluble vitamins yearly.

Referral and escalation. Pancreatic endoscopy with shock wave lithotripsy access; pancreatic surgery.