Clinicopathologic and Prognostic Significance of Gallbladder and Cystic Duct Invasion in Distal Bile Duct Carcinoma

Context.— The roles of the gallbladder and cystic duct (CD) invasions in distal bile duct carcinoma (DBDC) have not been well elucidated. Objective.— To define the characteristics and prognostic significance of gallbladder or CD invasions in patients with DBDC. Design.— Organ invasion patterns with clinicopathologic features were assessed in 258 resected DBDCs. Results.— CD invasions (N = 31) were associated with frequent concomitant pancreatic and/or duodenal invasions (23 of 31, 74%) and showed stromal infiltration (16 of 31, 52%) and intraductal cancerization (15 of 31, 48%) patterns. In only 2 cases, invasions with intraductal cancerization were observed in the gallbladder neck. Conversely, all pancreatic (N = 175) and duodenal (83) invasions developed through stromal infiltration. CD invasions were associated with larger tumor size (P = .001), bile duct margin positivity (P = .001), perineural invasions (P = .04), and higher N categories (P = .007). Patients with pancreatic or duodenal invasions had significantly lower survival rates than those without pancreatic (median, 31.0 versus 93.9 months) or duodenal (27.5 versus 56.8 months, P < .001, both) invasions. However, those with gallbladder or CD invasions did not have different survival times (P = .13). Patients with concomitant gallbladder/CD and pancreatic/duodenal invasions demonstrated significantly lower survival rates than those without organ invasions (P < .001). Conclusions.— Gallbladder invasions were rare in DBDCs as neck invasions with intraductal cancerization. CD invasions occurred by stromal infiltrations and intraductal cancerization, whereas all pancreatic and duodenal invasions had stromal infiltration patterns. Gallbladder and/or CD invasions did not affect survival rates of patients with DBDC, while pancreatic and duodenal invasions affected survival rates. Therefore, these differences in survival rates may originate from the different invasive patterns of DBDCs.