Chronic Pancreatitis
GENERAL PRINCIPLES
• Chronic pancreatitis represents inflammation, fibrosis, and atrophy of acinar cells resulting from recurrent acute or chronic inflammation of the pancreas.
• Most commonly seen with chronic alcohol abuse, it can also result from dyslipidemia, hypercalcemia, autoimmune disease, and exposure to various toxins. A rare inherited form (hereditary pancreatitis) can be associated with mutations in genes encoding cationic trypsinogen (PRSSl) or pancreatic secretory trypsin inhibitor (SPINKl).93
• Autoimmune pancreatitis (AIP) is an increasingly recognized subtype of chronic pancreatitis characterized by infiltration of IgG4-positive plasma cells in a classically sausage-shaped pancreas. AIP can be difficult to distinguish from pancreatic cancer on CT, but typically features diffuse narrowing of the main pancreatic duct without dilation.
DIAGNOSIS
Clinical Presentation
Chronic abdominal pain, exocrine insufficiency from acinar cell injury and fibrosis (manifesting as weight loss and steatorrhea), and endocrine insufficiency from destruction of islet cells (manifesting as brittle diabetes) are the main clinical manifestations.
Diagnostic Testing
LABORATORY TESTS
• Lipase and amylase may be elevated but are frequently normal. Bilirubin, alkaline phosphatase, and transaminases may be elevated if there is concomitant biliary obstruction.
• Indirect pancreatic function testing (such as secretin stimulation, fecal fat, and fecal elastase) can be obtained but are not widely available and difficult to perform.
IMAGING
• Calcification of the pancreas can be seen on imaging. Contrast-enhanced CT has a sensitivity of 75%- 90% and a specificity of 85% for the diagnosis of chronic pancreatitis; MRCP is equivalent and a suitable alternative.93
• Endoscopic ultrasound (EUS) has higher sensitivity for the diagnosis of chronic pancreatitis and is
particularly useful for evaluating lesions concerning for neoplasia in the setting of chronic pancreatitis.
TREATMENT
Medications
• Neuromodulators (TCAs, SSRIs) and pregabalin may improve symptoms and decrease reliance on narcotics. Opioids should only be used when all other treatments have failed.94
• Pancreatic enzyme supplements are the mainstay of management of pancreatic exocrine insufficiency in conjunction with a low-fat diet (lt;50 g fat per day), facilitating weight gain and reduced stool frequency.94 Enteric-coated preparations (Pancreaze, Zenpep, or Creon, one to two capsules with meals) are stable at an acidic pH.
• Fat-soluble vitamin supplementation may be necessary.
• Insulin therapy is generally required for endocrine insufficiency because the resultant diabetes mellitus is caused by insulin deficiency via beta cell loss rather than insulin resistance.
• When identified, treatment of the underlying disorder (e.g., hyperparathyroidism, dyslipidemia) is indicated.
• Alcohol and smoking cessation are essential. Performing procedures for pain relief in patients with chronic pancreatitis who are still smoking or consuming alcohol should be carefully considered.
• Steroids are used to treat autoimmune pancreatitis. Azathioprine can be considered to prevent relapse. Relapses may occur in the pancreas or biliary tree, although retreatment with steroids is effective at inducing remission.95
Other Nonoperative Therapies
• Patients with pancreatic duct obstruction from stones, strictures, or papillary stenosis may benefit from endoscopic therapies such as ERCP with pancreatic sphincterotomy, stricture dilation, pancreatic duct stenting, and/or extracorporeal shock wave lithotripsy (ESWL).
• Celiac plexus block can be used for short-term relief in selected patients with refractory pain.
• Surgery can be considered in selected patients who have a dilated pancreatic duct and fail medical and endoscopic treatment. Several surgical options for decompression exist (e.g., a lateral pancreaticojejunostomy if a dilated pancreatic duct is present). Whipple procedure is an option in rare cases.