69: Acute and Chronic Pancreatitis

Key Points

• Disease summary:

  • Pancreatitis is a syndrome of multiple etiologies with strong genetic influences. Genetic variants and environmental factors affect susceptibility to injury and modify the inflammatory response.

  • Acute pancreatitis (AP) describes the clinical syndrome associated with sudden onset of pancreatic inflammation, usually associated with pancreatic injury. The majority of cases are caused by gallstones or alcohol withdrawal and multiple less-common etiologies. Approximately 20% of AP is idiopathic and/or genetic.

  • Recurrent acute pancreatitis (RAP) describes a condition in which AP occurs more than once. The etiology of RAP is similar to AP, except for a lower incidence of treatable causes (eg, gallstones), and higher incidence of idiopathic etiologies.

  • Chronic pancreatitis (CP) is a syndrome of pancreatic inflammation lasting over 6 months. Until recently, alcohol was considered to be the etiology in 70% to 90% of cases, but this has been disproven. There is no consensus on classification of subtypes, in part because of overlap of etiologies (eg, smoking and heavy chronic alcohol use). All of the known susceptibility genes for CP are linked to dysregulation of intrapancreatic trypsinogen. Unusual subsets of CP include autoimmune pancreatitis (~5%), and some rare congenital syndromes.

  • Alcoholic pancreatitis (ACP) is pancreatitis associated with excessive alcohol ingestion, usually greater than 60 g per day. Smoking is common in alcohol drinking patients, and the effects of the two are likely synergistic. Genetic factors increase the risk of alcoholic pancreatitis (unpublished).

  • Hereditary pancreatitis (HP) is an autosomal dominant disorder usually caused by mutations in the cationic trypsinogen gene (PRSS1) that begins with typical AP, RAP, and eventually CP. The high penetrance rate and early age of onset are useful in distinguishing HP from other forms of CP.

  • CFTR-related pancreatitis is used to describe patients with CP that is linked to variant mutations in the cystic fibrosis transmembrane conductance regulator gene (CFTR) but who do not meet diagnostic criteria for cystic fibrosis. Atypical CF (aCF) is a general term that covers the mild CF spectrum, including recurrent bronchitis, or lung infections with no pancreatic involvement. aCF includes late age of diagnosis and borderline or low sweat chloride levels (<60 mEq/L). Symptoms may be limited to the pancreas, but male infertility and chronic sinusitis are also common overlapping features. Complex genotypes with CFTR plus pancreatic secretory trypsin inhibitor gene (SPINK1) variants are common and associated with pancreatitis only.

  • Autoimmune pancreatitis (AIP) is inflammation of the pancreas driven by immune dysregulation rather than pancreatic injury. It is often associated with elevated IgG4 level and may have a dramatic response to steroid treatment.

• Differential diagnosis:

  • Acute pancreatitis is usually suspected with sudden, severe abdominal pain. Differential diagnosis includes myocardial infarction, dissecting aortic aneurysm, mesenteric thrombosis and/or ischemia, volvulus, intussusceptions, penetrating gastric or duodenal ulcer, biliary colic and acute cholecystitis. The correct diagnosis is usually made by abdominal imaging and/or marked elevation of digestive enzymes in the blood.

  • Chronic pancreatitis is diagnosed with different criteria by different groups. ...