Morphological change of the tumor. A, The tumor was relatively well-circumscribed; the periphery may be the remaining blood vessel. B, Numerous spindle cells were arranged into sheets or swirling patterns. C, The spindle cells had marked cellular atypia, scattered multinucleated osteoclast-like giant cells were present amidst the spindle cells. D, The classic histological structure, the cords or nests epithelioid cells with intracytoplasmic vacuoles were focally present in extensive myxohyaline stroma.