CTSK and neoplasm: Immunohistochemical staining showed that the tumor cells were strongly positive for cathepsin-K (Fig. 2A), HMB45 (Fig. 2B) and TFE3 (Fig. 2C) and completely negative for PAX8, AE1/AE3, EMA, CD10, CK7, CK20, calretinin, inhibin, Melan A, S100, WT1, SMA, desmin, MyoD1, chromogranin, synaptophysin, CD56, CD68, D2-40, hepatocyte, GS and SALL4.