Mucoepidermoid carcinoma of the intrapancreatic common bile duct: immunohistochemical profile, prognosis, and review of the literature.

Mucoepidermoid carcinoma of the bile duct is a rare entity. Only one mucoepidermoid carcinoma from the common bile duct has been reported in the Korean literature. Herein, we present the first in the English literature. The tumor arose in the intrapancreatic (distal) common bile duct in an 83-year-old woman who presented with obstructive jaundice and elevated liver enzymes. The tumor invaded the underlying pancreas and peripancreatic adipose tissue and showed pagetoid spread into the extrapancreatic common bile duct and cystic duct. The tumor exhibited nests of malignant cells with diffuse CK7 and MUC1 positivity. The basal cells were p63 and CK5/6 positive. The luminal cells were stained with carcinoembryonic antigen, MUC5, and mucicarmine and were focally positive for CK20. There was focal MUC4 staining on the apical luminal border. The neoplastic cells were negative for MUC2 and HER2-neu. We discuss the clinical presentation, diagnostic features, immunohistochemical profile, and prognosis of mucoepidermoid carcinoma of the common bile duct. The features of this neoplasm are further compared with mucoepidermoid carcinoma of the hepatobiliary system, adenosquamous carcinoma, and mucoepidermoid carcinoma of other organs.