Figure 2: Cytomorphological and immunohistochemical aspects of primary oral melanoma of the gingiva. A) Oral melanoma of the upper gingiva formed by proliferation of epithelioid (resemble epithelial cells – red arrows) and plasmacytoid (resemble plasmacytoid cells – yellow arrows) neoplastic melanocytes, with some of them filled with melanin pigment (green arrow) (H&E, x400). Diffuse expression of S-100 protein (nuclear and cytoplasm stain) B) HMB-45 (cytoplasm stain) C) and Melan-A (cytoplasm stain) D) in primary oral melanoma of upper gingiva (Permanent red, x400).