Chronic pancreatitis. The problems of diagnostic criteria.

The diagnostic criteria for chronic pancreatitis proposed by the Japan Pancreas Society (JPS) classified chronic pancreatitis into (i) definite; (ii) probable, and (iii) possible chronic pancreatitis, excluding obstructive, inflammatory (autoimmune) and tumor-forming pancreatitis from the definition of chronic pancreatitis. In the JPS Criteria, imaging studies, pancreatic function tests, and histological findings are independent of each other, and thus the diagnosis of chronic pancreatitis is made if one of the criteria is satisfied, regardless of the etiology of the chronic pancreatitis. The current diagnostic criteria for chronic pancreatitis depend on abnormalities of the duct system, such as low bicarbonate output, dilation of main pancreatic duct and duct branches, and calculi in the ducts by imaging studies. We revealed that the difference between reversible and irreversible pancreatitis in experimental animals is dependent on the degree of damage of the duct epithelium where pancreas progenitor cells exist. Thus, chronic pancreatitis diagnosed by the current criteria based on abnormalities of the duct system is irreversible. In contrast, the epithelium of the ducts is usually preserved in obstructive and autoimmune pancreatitis in that both structural and functional changes recover almost completely when the obstruction is removed or the inflammatory changes disappear following steroid administration. Even in chronic pancreatitis defined as irreversible, there must be a reversible stage during its clinical course. There is a need to develop biological markers and/or imaging procedure to detect chronic pancreatitis at its reversible stage.