PAX8 and neoplasm: The immunohistochemical results were as follows: cytokeratin AE1/AE3, vimentin positive, paired box 8 (PAX 8) positive (Figure 2C), common acute lymphoblastic leukemia antigen 10 (CD 10) positive (Figure 2D), and Ki67 positive in approximately 8% of the tumor cells. These cells were negative for CK 7 and α-Methylacyl-coenzyme A racemase (P504s); weakly positive for carbonic anhydrase IX (CA IX); focally positive for cytokeratin 19 (CK 19); and negative for caudal-type homeobox 2 (CDX 2). The pathological diagnosis was metastatic RCC, clear cell type.