Fig. 4

Microscopic findings. a Microscopic findings of the tumor in the main pancreatic duct (MPD). The tumor showed a tubulopapillary growth pattern (arrowhead), and necrosis was observed (asterisk) (hematoxylin and eosin [H&E]; original magnification, × 50). b The tumor had invaded the stroma around the MPD (arrowhead) (H&E; original magnification, ×100). c The pancreatic duct was ruptured at the tail side of the tumor (arrow), and the fistula connected the MPD and the extrapancreatic scar tissue (arrowhead) (H&E; original magnification, × 50). d Microscopic findings of the tissues outside of the pancreas. Granulation and fibrosis were observed, and cancer cells were scattered (H&E; original magnification, × 100)