Pathology: BCOR-altered sarcoma

Fascicles of spindle-ovoid cells and nests of round cells

Pale amphophilic cytoplasm

Round-ovoid nuclei with vesicular chromatin, small nucleoli and mild pleomorphism; inconspicuous mitotic activity

Myxocollagenous stroma; delicate branching vasculature 

IHC: SATB2, CD99

RNA-seq: BCOR::CCNB3 gene fusion

Heterogeneous morphology including spindle cells in loose fascicles, and sheets of ovoid-round cells

Pale eosinophilic cytoplasm

Round-ovoid nuclei with small nucleoli and mild atypia; inconspicuous mitotic activity

Collagenous-myxoid stroma; delicate vasculature 

IHC: SATB2

RNA-seq: BCOR::CCNB3 gene fusion

Sheets-nests of epithelioid-ovoid cells

Pale eosinophilic cytoplasm

Round-ovoid nuclei with vesicular chromatin, small nucleoli and mild-moderate pleomorphism; mitotic activity

Prominent sinusoidal vasculature with occasional large thick-walled vessels

RNA-seq: BCOR::CCNB3 gene fusion