Epidermal Growth Factor Receptor Immunoreactivity in Gallbladder and Extrahepatic Biliary Tract Tumours

Elevated levels of epidermal growth factor receptor (EGFR), a transmembrane protein tyrosine kinase receptor, are found in carcinomas from various sites of the body. We investigated the expression o f EGFR in carcinoma of the gallbladder (n =13), common bile duct (n = 7) and ampulla o f Vater (n = 9). Non-malignant conditions investigated include chronic cholecystitis (n =11), gallbladder dysplasia (n = 3) and adenoma (n =1), and ampullary carcinoma in situ (CIS) (n = 2). Routine immunobistochemistry was employed using a monoclonal antibody against the EGFR protein. Immunostaining was assessed according to both intensity and extent of staining of cells. There was strong immunoreactivity for all gallbladder carcinoma and adenoma, the majority of common bile duct (n = 6; 86%) and ampullary (n = 6; 67%) carcinoma. In contrast, all cases o f gallbladder dysplasia, the majority of cases of chronic cholecystitis (n = 7; 64%) and ampullary CIS (n = 2; 67%) had only weak to moderate immunoreactivity. The pattern of immunoreactivity was one of diffuse cytoplasmic and membranous staining. In conclusion, EGFR expression is increased in both gallbladder, common bile duct and ampullary carcinomas but not in non-malignant conditions of the gallbladder and biliary tract. These findings suggest that EGFR overexpression occurs late in the sequential development of gallbladder and biliary tract cancers.