Spindle cells with herringbone pattern
Eosinophilic cytoplasm
Ovoid hyperchromatic nuclei with prominent nucleoli and moderate pleomorphism; brisk mitotic activity
Necrosis
Sheets of small round cells
Pale eosinophilic cytoplasm with indistinct cell borders
Monomorphic round nuclei with speckled chromatin and small nucleoli; mitotic activity
Cystic degeneration with pools of proteinaceous fluid
RNA-seq: negative
Sheets and nests of epithelioid cells
Amphophilic cytoplasm
Round-ovoid nuclei with moderate pleomorphism; mitotic activity
Prominent clefting; necrosis
RNA-seq: negative
Sheets of polygonal-spindle cells with a vague storiform-fascicular pattern
Abundant eosinophilic cytoplasm
Round-ovoid hyperchromatic nuclei with frequent multinucleation and marked pleomorphism; brisk mitotic activity
Necrosis; mild chronic inflammation