Corticosteroid-responsive diabetes mellitus associated with autoimmune pancreatitis: pathological examinations of the endocrine and exocrine pancreas.

: Histopathological changes of biopsied pancreata were examined in three diabetic patients with autoimmune chronic pancreatitis (ACP). We found intra- and periinsular mononuclear cell (MNC)—mainly CD8+ T cell—infiltration as well as MNC infiltration around the ductal cells. Islet β cell volume decreased significantly. Some ductal cells expressed insulin and insulin promoter factor-1 concomitantly in the affected pancreas. These findings provide new insight toward understanding the pathological mechanisms of corticosteroid treatment-responsive diabetes associated with ACP.