Fig. 3

Histopathologically, tumor cells consisted of a biphasic component morphology of epithelioid or rhabdoid and spindle-shaped (A, × 200). In the epithelioid or rhabdoid areas, there were numerous mitotic figures (20 mitoses per 10 high-power fields) (thin arrow), even atypical pathological mitoses (thick arrow) (B and C, × 400). A few of these neoplastic cells contained intracytoplasmic pigments (D, × 400). In the spindle areas, tumor cells had a fusiform morphology with a fascicular growth pattern (E, × 200), and showed fusiform nuclei, with dispersed chromatin, infrequent eosinophilic cytoplasm, numerous mitotic figures (17 mitoses per 10 high-power fields) and 1 or 2 prominent nucleoli (F, × 400). Melanoma in situ in the superficial of nasal mucosa and its transition to the epithelioid area of the tumor in submucosa were observed (H, × 200)