Microscopically, the tumor mass consisted of a dimorphic population of cells that were separated into lobules by trabeculae of fine fibrovascular stroma. Generally, the tumor cells were polyhedral, had lightly eosinophilic and often vacuolated cytoplasm. Nuclei were round to oval and the chromatin was finely granular. Some cells with a small, dense, spindle-shaped nucleus and scanty cytoplasm were also seen. In addition, few mononuclear tumor giant cells with large, oval or sausage-shaded nuclei were observed. A few foci of coagulation necrosis were seen in the tumor.