PAX2 and neoplasm with perivascular epithelioid cell differentiation: Though tRCC is distinguished from PEComa by its retention of detectable keratin and PAX8 expression in clinical practice, the downregulated expression of PAX8 expression in the PTK tRCC model and the frequent underexpression of cytokeratin and EMA expression seen in human tRCC18 led us to test whether there is partial PAX8 and PAX2 loss in human tRCC samples that had not been previously appreciated.