Fig. 2

Pathological findings of the tumor. a: In well-differentiated areas, there were many vascular lumens of different sizes, dilated partly and filled with blood (4×); b: The lumens were lined with flattened or obese mildly atypical endothelial cells (10×); c and d: Some areas tumor cells were lined in an irregular labyrinth cavity structure, with the lumen expanding and anastomosing with each other. It was covered with one or more layers of swollen endothelial cells, showing papillary and boot-nail protruding into the lumen (10×). e: In the poorly differentiated areas, fusiform and epithelioid tumor cells formed solid nests without obvious channel and some tumor cells, which showed significant pleomorphism with vacuolated nuclei and obvious nucleoli scattered in patch. Mitotic were 5 to 10 per 10 high power field and included pathological karyokinesis (10×). f: Vacuoles cells that similar to adipoblast cells were observed in focal lesions (10×)