Figure 1

Enterovirus (EV) infection of islets and exocrine pancreas in recent-onset diabetes and long-duration diabetes of slowly progressive type 1 diabetes mellitus (SPIDDM). (a) Low-magnification view of the pancreas in recent-onset diabetes (Case SP10; duration: 3 months), stained for VP1. Islet cells (b) and exocrine cells (c) are positive for EV capsid protein (VP1, brown). VP1-positive acinar cells are rarely found. Inset: pancreatic duct epithelial cells (arrows) are intact, without features of pancreatic intraepithelial neoplasia (PanIN). (b) Magnified view of (b). Some islet cells (arrows) and acinar cells beside the islet (arrowheads) are positive for VP1. (c) Magnified view of (c). Two acini (arrows) show “ring-like” arrangements, reminiscent of the start of acinar-to-ductal-metaplasia (ADM). (d) Low-magnification view of the pancreas with a long duration of SPIDDM (Case SP8; duration: 14 years) stained for VP1. A PanIN (arrow and inset)-centered lobe demarcated by fibrous tissue (dashed lines) includes many islets, one of which is marked with (e), and VP1-positive exocrine acinar cells constitute clusters (circled), one of which is marked with (f). Note that parenchymal tissues in the PanIN lobe demarcated by a dashed line are atrophied due to fibrosis and contain a relatively increased number of islets (arrowheads). (e) Magnified view of (e) in (d). Islet cells are positive for VP1 (arrows) surrounded by infiltrated mononuclear cells (asterisks). Note that the VP1-positive acinar cell cluster (arrowhead) touches the islet, suggesting close association with the islet. (f) Magnified view of (f) in (d). Most exocrine VP1-positive acinar cells (brown, asterisks) show a flat shape with ring-like arrangements, a feature of ADM.