Fig. 6

Microscopic findings of the tumor. a Hematoxylin–eosin staining (×40). b Hematoxylin–eosin staining (×100). These figures show numerous long spindle-shaped cells with relatively high cell density in the form of palisade, complex, or diffusion. Tumor cells maintain acidophilic and clear endoplasmic reticula, whereas some cells with mild-to-moderate nuclear grades with strange or giant form were scattered. The mitotic activity was 30–40/10 high-power field (HPF). c Hematoxylin–eosin staining (×40). d Hematoxylin–eosin staining (×100). These figures show metastasis of the dissected lymph nodes