Figure 6.

Woman, 22 years. An ulcerated nodule of the right flank (A) dermoscopically characterized by keratoacanthoma-like features with vessels surrounded by a white halo (B). Histopathologically, the tumor has an irregularly nodular, exophytic silhouette with an epidermal “collarette”, a superficial crust, and a “brisk” inflammatory infiltrate in the dermis (C; hematoxylin–eosin, ×25); the superficial nests are very irregularly confluent with no sharp circumscription from the overlying epidermis (D; hematoxylin–eosin, ×250); dermal melanocytes show a “spitzoid” morphology, with spindle (E; hematoxylin–eosin, ×400) and epthelioid (F; hematoxylin–eosin, ×400) cells, both with reatively abundant and eosinophilic cytoplasms. In spite of the severe architectural atypia, the proliferation rate of the tumor (Ki67-positive dermal melanocytes) is low (G) ×250); however, the tumor is not an atypical Spitz tumor, but a classical nodular melanoma because it is positive to the antibody anti-BRAFv600e-mutated protein (H) ×250).