Although rare, autoimmune pancreatits, also known as lymphoplasmacytic sclerosing pancreatits, can clinically mimic pancreatic cancer. Autoimmune pancreatitis, as the name suggests is a disease that is: 1) characterized by inflammation of the pancreas (“pancreatitis”), and 2) believed to be caused by the body’s immune system abnormally reacting against the body’s own cells in the pancreas (“auto” means self or same).
Autoimmune pancreatits is pretty darn rare. A hospital survey from Japan, estimated that less than one person per 100,000 has autoimmune pancreatitis. Most patients are elderly, with an average age of 68, but teenagers have been diagnosed with the disease as well as octogenarians. Unlike most other autoimmune diseases, men develop autoimmune pancreatitis more commonly than do women (the male to female ratio is 4 to 1). Most patients do not present with signs and symptoms of pancreatitis, instead most patients develop signs and symptoms that are more suggestive of pancreatic cancer. These would include jaundice (an abnormal yellowing of the white part of the eyes), and diabetes mellitus (sugar diabetes). A CT scan is often taken and it can reveal a localized “sausage-like” enlargement of the pancreas, a finding suggestive of pancreatic cancer. As a result, many patients with autoimmune pancreatitis are often felt to have pancreatic cancer. A blood test can be helpful as many, although certainly not all, patients with autoimmune pancreatitis have elevated serum “IgG4 levels.”
Autoimmune pancreatitis can be associated with immune injury to other organs, and some patients also develop a swelling of their salivary glands, kidney problems, and a scarring of the internal abdomen (called retroperitoneal fibrosis).
Because autoimmune pancreatits so closely mimics pancreatic cancer, many patients with autoimmune pancreatits are taken to surgery and have the abnormal portion of their pancreas removed. In these cases the pathology of the pancreas can be diagnostic. It shows three features- 1) a mixed inflammatory cell infiltrate composed of plasma cells and lymphocytes, 2) inflammation centered on the pancreatic ducts, and 3) inflammation involving the veins of the pancreas (“venulitis”). In questionable cases a special stain for IgG4 can be performed and it will label the inflammatory cell infiltrate in the pancreas helping to establish the diagnosis.
Autoimmune pancreatits is important to recognize because some patients respond to steroid therapy (30–40 mg/day of prednisolone). As clinicians become familiar with this rare disease it is hoped that more and more patients will be diagnosed without the need for surgery.
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