Variable cellularity; spindle cells with storiform-fascicular pattern
Eosinophilic cytoplasm with long tapering processes
Ovoid nuclei with occasional atypia; inconspicuous mitotic activity
Collagenous stroma
IHC: CD34, S100
RNA-seq: CHD9::VGLL3 gene fusion
Variable cellularity; spindle cells with storiform-fascicular pattern
Eosinophilic cytoplasm with long tapering processes
Ovoid nuclei with occasional atypia; pseudonuclear inclusions; inconspicuous mitotic activity
Collagenous-myxoid stroma
RNA-seq: CHD7::VGLL3 gene fusion
Circumscribed; variably cellular; spindle cells with storiform-fascicular pattern
Eosinophilic cytoplasm with long tapering processes
Ovoid nuclei with occasional pleomorphism; inconspicuous mitotic activity
Collagenous-myxoid stroma
IHC: S100, SOX10
RNA-seq: CHD7::VGLL3 gene fusion
Circumscribed
Spindle cell neoplasm with fascicular-storiform pattern
Pale eosinophilic cytoplasm
Round-ovoid nuclei with mild atypia and scattered hyperchromasia and pseudonuclear inclusions; inconspicuous mitotic activity
Variable collagenous-myxoid stroma and delicate vasculature
IHC: S100, SOX10, CD34, claudin-1, GLUT-1, glial fibrillary acid protein
RNA-seq: CHD7::VGLL3 gene fusion
PMID: 19623031, 33649458
Circumscribed
Spindle-stellate cells with loose fascicular pattern
Eosinophilic cytoplasm with tapering bipolar processes
Monomorphic ovoid nuclei; inconspicuous mitotic activity
IHC: S100, SOX10
RNA-seq: CHD9::VGLL3 gene fusion
PMID: 19623031, 33649458
Circumscribed
Spindle cell neoplasm with loose fascicular pattern
Eosinophilic cytoplasm with tapering bipolar processes
Ovoid hyperchromatic nuclei with mild atypia and occasional pseudonuclear inclusions; inconspicuous mitotic activity
IHC: S100, SOX10
RNA-seq: CHD9::VGLL3 gene fusion
PMID: 19623031, 33649458
Spindle cell neoplasm with fascicular-storiform pattern
Pale eosinophilic cytoplasm
Ovoid, occasionally elongated, nuclei with minimal atypia; inconspicuous mitotic activity
Variable collagenous stroma and delicate vasculature
RNA-seq: GAB1::ABL1 gene fusion
* Despite morphologic and immunohistochemical overlap with hybrid schwannoma/perineurioma, it is conceivable this may ultimately represent a distinct entity (PMID: 34036664)