Pathology: hybrid nerve sheath tumours

Hybrid schwannoma/perineurioma

  • 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

Hybrid schwannoma/perineurioma

  • 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

Hybrid schwannoma/perineurioma

  • 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

Hybrid schwannoma/perineurioma*

  • 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)