Recurrent attacks of autoimmune pancreatitis result in pancreatic stone formation

Autoimmune pancreatitis has been characterized by irregular narrowing of the main pancreatic duct and sonolucent swelling of the parenchyma, both of which are due to lymphoplasmacytic inflammation at the active stage of the disease, and by the absence of pancreatic stone formation. The aim of the present study was to confirm or deny whether or not this disease is progressive with recurrent attacks, resulting in pancreatic stone formation like ordinary chronic pancreatitis.

Forty-two patients, 36 of whom were treated with prednisolone, were followed up for periods longer than 12 months (median follow-up period: 54.5 months, range: 13-111 months) by regular interview and examination of their medical records for laboratory tests and image tests.

Eleven patients (26.2%) who were treated with prednisolone showed recurrent attacks during median follow-up periods of 22 months. Eight patients (19%) showed the formation of pancreatic stones during the follow-up periods. Because 6 of 11 patients (54.5%) who suffered relapse showed pancreatic stone formation, it is significantly associated with relapse in comparison with nonrelapse (p= 0.0019).

Contrary to previous reports, we observed both relapse and pancreatic stone formation in some patients with autoimmune pancreatitis, which suggests that autoimmune pancreatitis has the potential to be a progressive disease with pancreatic stones.