Sheets of polygonal-spindle cells of varying size
Abundant amphophilic cytoplasm
Round-ovoid nuclei with prominent nucleoli, marked pleomorphism and frequent multi-nucleation; conspicuous mitotic activity
Interspersed epithelioid-rhabdoid cells with abundant eosinophilic cytoplasm; eccentric nuclei
IHC: desmin, myogenin
FISH: MDM2 non-amplified