Clinicopathologic classification of congenital cystic dilatation of the common bile duct.

From 1970 to 1975, 103 patients with a localized dilatation of the biliary passages were treated at the First Department of Surgery of Kyoto University Medical Center. Of the 103, 101 had congenital cystic dilatation of the common bile duct (Alonso-Lej type I). These dilatations were classified into two sub-types, "infant type" and "adult type," based on the anatomic location and clinical features. Infant type cyst was typically large cyst of the choledochus and most common in infancy and childhood. Adult type cyst was fusiform dilatation of the biliary tract, and most common in adults. Gallstones were seen in most of the patients with this type cyst.