Similarly, CK19—a type I acidic keratin—is expressed in a variety of glandular epithelial tissues including the gastrointestinal tract, bile ducts, respiratory epithelium, and salivary glands [6] In malignancy, CK19 expression is retained and widely used as a diagnostic marker, for example in thyroid carcinoma [13] and in distinguishing hepatocellular carcinoma from cholangiocarcinoma [14]. This evidence concerns the gene KRT19 and cholangiocarcinoma.