Pathology: perineurioma

Perineurioma

  • Lobulated with loose fascicular pattern

  • Spindle cells with pale amphophilic cytoplasm and long bipolar processes

  • Monomorphic ovoid nuclei; inconspicuous mitotic activity

  • Clefting artifact

  • IHC: claudin-1, CD34, epithelial membrane antigen, GLUT1

Perineurioma

  • Circumscribed; loose fascicular-whorled pattern

  • Spindle cells with pale amphophilic cytoplasm and long bipolar processes

  • Monomorphic ovoid nuclei; inconspicuous mitotic activity

  • Central cystic change

  • IHC: GLUT1, claudin-1

Perineurioma

  • Lobulated with loose fascicular pattern

  • Spindle cells with pale amphophilic cytoplasm and long bipolar processes

  • Monomorphic ovoid nuclei; inconspicuous mitotic activity

  • Intervening bands and lobules of collagen

  • IHC: CD34, epithelial membrane antigen, GLUT1, claudin-1

Perineurioma

  • Spindle cells with fascicular-storiform pattern

  • Pale amphophilic cytoplasm and long bipolar processes

  • Monomorphic ovoid nuclei; inconspicuous mitotic activity

  • Intervening collagen bands

  • IHC: CD34, claudin-1, GLUT1

Perineurioma, malignant

  • Remote history of perineurioma

  • Heterogeneous with areas of hyper- and hypo- cellularity

  • Ovoid cells arranged in sheets with scant amphophilic cytoplasm and indistinct cell borders; ovoid nuclei with mild atypia; mitotic activity

  • Spindle-stellate cells with reticular pattern; eosinophilic cytoplasm; ovoid nuclei with mild atypia; inconspicuous mitotic activity

  • Spindle cell arranged in fascicles with pale amphophilic cytoplasm and long bipolar processes; ovoid nuclei with mild atypia; inconspicuous mitotic activity; abundant intervening collagen

  • Necrosis

  • IHC: CD34