Histopathological studies of mucin-producing carcinoma of the bile duct

Mucin-producing carcinoma (MPC) of the bile duct produces large amounts of mucin. As many aspects of the characteristic biological pattern of invasion and origin of this tumor are unclear, we investigated its pathological molecular biology and association with peribiliary glands. Molecular biologically, MPC with multiple tumors had a higher tumor proliferation potency than MPC consisting of a single tumor. Even multiple tumors with high malignant potential showed little evidence of lymphatic invasion, and there was little venous or perineural invasion. Findings in regard to the peribiliary glands (PGs) suggested that PGs are involved in the origin and extension of MPC. Mucinous PGs under the main tumor were exhibited beneath the dysplasia and non-neoplastic epithelium, whereas mucinous PGs under MPC with multiple tumors contained neoplastic cells. PGs secreted large quantities of mucin. We conclude that neoplastic cells in PGs caused cell proliferation toward the bile duct lumen.