PAX8 and renal cell carcinoma: These metastases were positive for PAX8, that is a well-established marker for primary and metastatic RCC (Ozcan et al., 2012; Shen et al., 2012) and CDH16, which is a specific renal protein (Shen et al., 2012), while they were negative for the bile ducts and cholangiocarcinoma marker CK7 (Cytokeratin 7), consistent with their renal origin (Figure 2L).