Fig. 3.

Histological examination revealed a melanocytic neoplasm with moderate mitotic activity and infiltrative growth pattern. Conventional hematoxilin and eosin staining (A; x100) shows lack of substantial cytologic atypia; a mitotic figure is depicted in the inset. Moderate MIB1 staining supports higher proliferative potential (B; x400). Melanocytic differentiation is disclosed by melanin pigmentation (C; Fontana-Masson staining, x400), and immunohistochemical positivity for the melanocytic markers HMB45 (D; x400) and Melan A (E; x200). Staining for glial fibrillary acidic protein (F; GFAP, x100) highlights the invasive tumor growth pattern, with unstained tumor cells and positively stained infiltrated central nervous tissue.