Fig. 3

Histopathological examination. a Hematoxylin and eosin staining of the specimen showed large, densely packed cells with spindle, over, polygonal, or bizarre shapes. The cells had abundant amphophilic cytoplasm, large vesicular nuclei, and a few prominent nucleoli. Mitotic figures were scattered throughout the tumor (× 200). b Immunohistochemistry findings showing positivity for vimentin in the tumor cells (× 200). c Immunohistochemistry findings showing positivity for CD31 in the tumor cells (× 200). d Immunohistochemistry findings showing positivity for factor VIII in the tumor cells (× 200)