Fig. 2

A and B The low magnification shows a heavily pigmented tumor infiltrating into the surrounding skeletal muscle fibers (H&E, A:40×, B: 100×); C the tumor is composed of predominantly medium to large-sized epithelioid cells with heavily pigmented cytoplasm obscuring nuclei, some of them have large vesicular nuclei with prominent nucleoli and abundant cytoplasm, Spindled blue nevus-like cells constitute the minor component, rare mitotic activity are seen (H&E, 400×); D Tumor cells were positive for S-100 protein (Red Chromogen: 200×); E Tumor cells were positive for MART-1/MELAN-A (Red Chromogen: 200×); F Tumor cells were positive HMB-45 (Red Chromogen: 200×)