Lobulated; epithelioid-spindle cells with fascicular-storiform pattern
Pale amphophilic cytoplasm
Ovoid nuclei with small nucleoli and mild atypia; rare mitotic activity
Central cystic haemorrhagic cavity; haemosiderin deposition; peripheral lymphocytic cuff
RNA-seq: EWSR1::ATF1 gene fusion
Circumscribed; fascicles of epithelioid-spindle cells
Pale amphophilic cytoplasm
Ovoid-elongated nuclei with small nucleoli and mild atypia; inconspicuous mitotic activity
Central cystic haemorrhagic cavity; abundant haemosiderin deposition; peripheral lymphocytic cuff
IHC: desmin
RNA-seq: EWSR1::CREB1 gene fusion
Epithelioid-spindle cells with storiform pattern
Pale amphophilic cytoplasm
Ovoid nuclei with small nucleoli and mild atypia; inconspicuous mitotic activity
Focal myxoid-collagenous stroma; interspersed lymphoplasmacytic infiltrate
IHC: desmin, epithelial membrane antigen
RNA-seq: EWSR1::CREB1 gene fusion
Circumscribed
Spindle cells with fascicular pattern
Pale eosinophilic cytoplasm
Ovoid nuclei with small nucleoli and minimal atypia; inconspicuous mitotic activity
Occasional broad collagen bands; incomplete lymphocytic cuff
SS: Prussian blue
IHC: smooth muscle actin, desmin, H-caldesmon, epithelial membrane antigen
RNA-seq: EWSR1::ATF1 gene fusion
Multinodular; fascicles of epithelioid-polygonal cells
Pale eosinophilic cytoplasm
Ovoid nuclei with small nucleoli, vesicular chromatin and mild atypia; inconspicuous mitotic activity
Central cystic cavity; abundant haemosiderin deposition; siderophages and foamy histiocytes; peripheral lymphocytic cuff
FISH: EWSR1-rearrangement
Circumscribed; ovoid cells in short fascicles and whorls
Pale amphophilic cytoplasm
Ovoid nuclei with small nucleoli, vesicular chromatin and mild atypia; inconspicuous mitotic activity
Central cystic cavity; abundant haemosiderin deposition; siderophages and foamy histiocytes; peripheral lymphocytic cuff
IHC: desmin
RNA-seq: EWSR1::CREB1 gene fusion
Ovoid-spindle cells with vague storiform pattern
Pale amphophilic cytoplasm
Ovoid nuclei with small nucleoli, vesicular chromatin and mild atypia; inconspicuous mitotic activity
Peripheral hint of haemorrhagic cavity; interspersed lymphocytes and histiocytes
RNA-seq: EWSR1::CREB1 gene fusion