Pathology – nonmalignant

Pathology is the study of the structural and functional changes in living organisms caused by disease.  In many organs, pathology is caused by infections or inflammation.  In 1896, an Austrian pathologist named Professor Hans Chiari suggested that, in most cases, no infectious organism could be found in the inflamed pancreas, and the likely cause of injury and inflammation was premature activtion of the digestive enzymes, leading to auto–or self–digestion of the pancreas.  This theory was greatly strengthened 100 years later in 1996, when Professor Whitcomb and his team discovered that mutations in the trypsinogen gene (coding for the master digestive enzyme, trypsin) that caused it to be overly active could lead to hereditary pancreatitis. Hereditary pancreatitis is a disease that begins with acute pancreatitis, later progresses to chronic pancreatitis, and in some cases leads to pancreatic cancer later in life.  The most common nonmalignant pathologies of the pancreas are acute inflammation and its pathologic complication (acute pancreatitis) and chronic inflammation and its pathologic complication(chronic pancreatitis).

This photomicrograph shows the progression from a normal pancreas to chronic pancreatitis and inflammation driving fibrosis (scarring).

Progressive loss of normal acinar cells (and later islet cells – marked as “*”) as chronic inflammation and fibrosis (light colored material) replaces the normal cells.

The major risk factors for chronic pancreatitis are genetic and severe bouts of acute pancreatitis; alcohol consumption and smoking typically cause a more rapid progression from normal to abnormal.

The major complications of chronic pancreatitis include loss of acinar cells leading to maldigestion of nutrients, inflammation and injury to nerves causing varying degrees of pain, activation of a stellate cells (a healing type of immune cell) that leads to fibrosis (scarring), sclerosis (hardening of the pancreas) and distorted, dilated ducts.  Inflammation can also damage islet cells, which may eventually cause diabetes mellitus.  Additionally, inflammation may lead to the formation of calcium stones that can be located in the ducts or in the tissue.  Moreover, injury to the pancreatic cells can damage DNA, which may potentially  cause cancer (see Pathology – malignant).

Other forms of nonmalignant pancreatic pathology include genetic disorders (e.g. Shwachman-Diamond syndrome), infarction from the loss of blood flow (occurring during acute pancreatitis), fatty pancreatic replacement, cyst formation, duct blockage, and inflammation from autoimmune conditions and infections (viruses, bacteria or parasites).