Figure 4. (A) Tumor cells with nucleoli and swelling anisocytosis of different sizes densely proliferating in sheet-like and large-sized follicle-like forms. The lesion was accompanied by the deposition of melanin pigment. Cellular proliferation of melanocytes was observed on the intraepithelial basal side of the melanoma around the tumor, but no development of malignant melanoma was observed (hematoxylin and eosin, ×20). (B) Immunohistochemical staining for MelanA was positive (×200). (C) Immunohistochemical staining for HMB45 was positive (×200). (D) Immunohistochemical staining for S100 was positive (×200).