The immunohistological stainings of the bile duct tumor showed the cytokeratin (CK)7-negative, CK20-positive, caudal-type homeobox 2 (CDX2)-positive and special AT-rich sequence-binding protein (SATB2)-positive, uncovering that the bile duct tumor originated from the sigmoid colon carcinoma (Fig. 3). This evidence concerns the gene SATB2 and bile duct neoplasm.