Fig. 3.

(a) Macroscopic findings of the duodenum, showing a fungiform exposed protruding mass, 50 × 40 × 35 mm, located in the periampulla of the duodenum. (b) Microscopically, the tumor was located mainly in the ampullary region, originating from the terminal segment of the common bile duct in the ampullary region. (c) Histologic examination showed that the tumor consisted of sheets of anaplastic round, ovoid or spindle giant cells admixed with multinucleated osteoclast-like giant cells. (d) Carcinoma in situ was observed, continuously spreading from the tumor at the terminal segment of the common bile duct to the common hepatic duct and cystic duct.