Differentiating pure epithelioid PEComa/epithelioid angiomyolipoma from TFEB-rearranged renal cell carcinoma is challenging, as the two entities share the immunohistochemical expression of cathepsin K and melanocytic markers, such as HMB45 and Melan-A. The gene discussed is CTSK; the disease is neoplasm with perivascular epithelioid cell differentiation.