Figure 2

Macroscopic and microscopic findings of the resected specimen. A) Macroscopic findings of the resected specimen. The pancreas head was cut in the direction shown in the illustration. Because the main pancreas duct was markedly curved in the pancreas head, a proximal section (pMPD) and a distal section (dMPD) are seen in the same section. A cross section of the intra-pancreatic bile duct is seen (indicated as BD). In this section, one of the dilated branch pancreas ducts is seen (indicated as BPD). B) Microscopic findings of the resected specimen (hematoxylin and eosin stain, a loupe observation of the rectangle in macroscopic finding above). Almost all epithelia of both the main and branch pancreas ducts were composed of intraductal papillary mucinous adenoma with mild atypia. BPD and pMPD indicates dilated branch pancreas duct and proximal main pancreas duct, respectively. There is a demarcated area (surrounded by arrows) consisting of endocrine tumor. C) Microscopic findings of the intraductal papillary mucinous adenoma (x460 nm/pix). D) Microscopic findings of the neuroendocrine area (x460 nm/pix). E-G) Immunohistochemical examination of the endocrine cells was positive for chromogranin A (E), synaptophysin (F), and glucagon (G). H) Immunohistochemical examination of Ki-67. The positivity rate was less than 2%.