Primary; deep seated thigh mass
Sheets of polygonal-round cells
Scant amphophilic cytoplasm
Round-ovoid nuclei with vesicular chromatin, prominent nucleoli and mild-moderate pleomorphism; brisk mitotic activity
Necrosis
IHC: CD99, keratin (AE1/AE3)
RNA-seq: BRD3::NUTM1 gene fusion
PMID: 29356724, 30407212, 30723300