Circumscribed; fascicles-whorls of spindle-stellate cells
Plump eosinophilic cytoplasm in cells concentrically arranged around vessels; intervening cells have scant cytoplasm and long tapering processes
Monomorphic ovoid nuclei; inconspicuous mitotic activity
Ectatic medium-sized vessels with variable mural thickness lined by plump vacuolated endothelial cells
Intervening stroma is myxoid with occasional mast cells
IHC: H-caldesmon
Spindle cells with fascicular-storiform pattern
Eosinophilic cytoplasm
Ovoid nuclei with small nucleoli; inconspicuous mitotic activity
IHC: desmin, smooth muscle actin, H-caldesmon, keratin (AE1/AE3)
RNA-seq: SRF::CITED1 gene fusion
PMID: 33021523
Circumscribed; cellular spindle cell fascicles
Pale amphophilic cytoplasm
Ovoid nuclei with vesicular chromatin and small nucleoli; rare mitotic activity
Prominent dystrophic calcification
IHC: smooth muscle actin, desmin, H-caldesmon
RNA-seq: SRF::C3orf62 gene fusion
PMID: 28248815
Circumscribed; cellular spindle cell fascicles
Pale amphophilic cytoplasm
Ovoid nuclei with vesicular chromatin and small nucleoli; occasional mitotic activity
IHC: smooth muscle actin
RNA-seq: SRF::RELA gene fusion
PMID: 28248815
Circumscribed; cellular spindle cell fascicles
Pale eosinophilic cytoplasm
Ovoid nuclei with small nucleoli; rare mitotic activity
Delicate curvilinear vasculature
RNA-seq: SRF::YAP1 gene fusion*
* To date unreported in the literature
Spindle cell fascicles
Pale eosinophilic cytoplasm
Ovoid nuclei with occasional inclusions; inconspicuous mitotic activity
Occasional collagenous bands
RNA-seq: SRF::RELA gene fusion