We report a case of a male patient with autoimmune pancreatitis in whom biochemical examination revealed high plasma chromogranin A concentrations, histological demonstration of a small lymphocytic infiltrate and rapid decrease in size of the pancreatic mass following short-lasting therapy with methylprednisolone. To our knowledge, this is the first patient with autoimmune pancreatitis who had a simultaneous increase of serum chromogranin A levels, circulating and urinary serotonin concentrations and urine 5-hydroxyindoleacetic acid concentrations. This is one of the few cases of mass forming pancreatitis with small lymphocytic infiltrate found in a Caucasian patient and rapid decrease in size of the pancreatic mass following short-lasting therapy with methylprednisolone.