CTSK and neoplasm with perivascular epithelioid cell differentiation: The immunohistochemical analysis of renal TFE3-rearranged PEComas consistently shows a robust expression of cathepsin K (99%) and melanogenesis markers (HMB45 91% and MART1/MELAN A 80%) along with negativity for PAX8, cytokeratins, and S100 (Figure 6).