PAX8 and cholangiocarcinoma: Clinically relevant tumors with near complete absence of PAX8 staining (< 1%) included for example all subtypes of breast cancers, gastric adenocarcinoma, prostatic adenocarcinoma, hepatocellular carcinomas, cholangiocarcinoma, gallbladder adenocarcinoma, pulmonary adenocarcinoma, neuroendocrine neoplasms, and small cell carcinomas of various sites.