Fascicles of spindle-epithelioid cells
Pale amphophilic cytoplasm
Ovoid nuclei with macronucleoli, vesicular chromatin and mild pleomorphism; mitotic activity
Intersecting collagen bands; melanin pigment; multinucleated giant cells
RNA-seq: EWSR1::ATF1 gene fusion
Fascicles of spindle-epithelioid cells
Pale amphophilic-clear cytoplasm
Ovoid nuclei with macronucleoli, vesicular chromatin and scattered pleomorphism; mitotic activity
Occasional collagen bands
IHC: S100, SOX10, HMB45, Melan-A
RNA-seq: EWSR1::ATF1 gene fusion
Nests and fascicles of spindle-epithelioid cells
Pale amphophilic cytoplasm
Monomorphic round-ovoid nuclei with macronucleoli; occasional mitotic activity
Intersecting collagen bands
IHC: S100, SOX10, HMB45, Melan-A
RNA-seq: EWSR1::ATF1 gene fusion
Fascicles of spindle-epithelioid cells
Pale amphophilic cytoplasm
Monomorphic round-ovoid nuclei, with macronucleoli; mitotic activity
Scattered melanin pigment; intersecting collagen bands and rare multinucleated giant cells
IHC: S100, SOX10, HMB45, Melan-A
RNA-seq: EWSR1::ATF1 gene fusion
Fascicles of spindle-epithelioid cells
Pale amphophilic cytoplasm
Ovoid nuclei, with macronucleoli and moderate pleomorphism; mitotic activity
Intersecting collagen bands
RNA-seq: EWSR1::ATF1 gene fusion
Fascicles of spindle-epithelioid cells
Pale amphophilic cytoplasm
Monomorphic round-ovoid nuclei, with macronucleoli; mitotic activity
Intersecting collagen bands; rare multinucleated giant cells
IHC: S100, HMB45
RNA-seq: EWSR1::ATF1 gene fusion