Fig. 4

Morphological evaluation derived from pathological findings. No adenomas were observed, suggesting a hyperplasia–dysplasia–carcinoma sequence carcinogenic mechanism. No. 1: Main part of the carcinoma (C) in the common channel. No. 2: The depiction of front between hyperplasia (H) area, dysplasia (D) area, and carcinoma (C) area is observed in the common channel. No. 3: Hyperplasia (H) in the common bile duct. There was no evidence of increased nuclear-to-cytoplasmic ratio, increased nuclear chromatin and loss of nuclear polarity, or cell overlap. MP, Muscularis propria; Panc., Pancreas