Immunophenotypic features: overexpression of TFEB genes frequently drives abnormal expression of melanocyte-associated antigens (HMB45, Melan-A) and osteoblast histone k (cathepsin k); overexpression of cathepsin k (p < 0.000), HMB45 (p < 0.000), and Melan-A (p = 0.028) is more commonly found in TFEB-translocated renal cell carcinoma. The gene discussed is CTSK; the disease is renal cell carcinoma.