Autoimmune pancreatitis is an entity that has recently been included in the differential diagnosis of chronic pancreatitis-pancreatic mass. The presence of diffuse, irregular Wirsung's duct stenosis, together with high levels of IgG4, the existence of certain autoantibodies and lymphoplasmacytic infiltration of the pancreas are key factors in the diagnosis. An early diagnostic suspicion and multidisciplinary collaboration are vital in these cases to avoid unnecessary surgery as the differential diagnosis is established with such entities as pancreas cancer, chronic pancreatitis, primary biliary cirrhosis or primary sclerosing cholangitis. Autoimmune pancreatitis has an excellent response to steroid therapy, with complete resolution of clinical, analytical and radiological parameters, as occurred in our patient. The very few cases reported so far suggest the need for the elaboration of long-term follow-up studies to determine the prognosis and frequency of its association with other diseases.