Tag: pilocytic astrocytoma

Grading classifies different histological types and also within each type. Arabic numerals (1, 2, 3, 4) are used instead of Roman numbers.

Eg: Astrocytoma, IDH Mutant, CNS WHO Grade 2

Total 4 grades only.

Grade 1

Circumscribed tumours.

  • Pilocytic astrocytoma (Well circumscribed)
  • Diffuse astrocytoma MYB altered
  • Angiocentric glioma
  • PLNTY
  • Multinodal & vacuolating neuronal tumour
  • Subependymoma
  • Myxopapillary ependymoma
  • Meningioma (most of them except 4 below)
  • SFT (can be 1, 2, 3)
  • Chordoma
  • Ganglioglioma

Grade 2, 3 (3 = anaplastic)

2 = infiltrating.
3 = evidence of malignancy. eg: Anaplastic ependymoma/astrocytoma/oligodendroglioma

  • Astrocytoma, IDH Mutant
  • Oligodendroglioma, IDH Mutant
  • Pleomorphic xanthoastrocytoma
  • Chordoid glioma (all mixed gliomas)
  • Ependymoma
  • Supratentorial, Posterior fossa Ependymoma
  • G2 meningiomas: Clear cell, Chordoid, Atypical Meningiomas
  • G3 meningiomas: Rhabdoid, Papillary and anaplastic meningioma
  • Central neurocytoma
  • Hemangiopericytoma

Grade 4

Malignant, aggressive, rapid growth and necrosis.

  • Glioblastoma, Gliosarcoma
  • Diffuse midline and diffuse hemispheric glioma
  • All “-blastomas”.
    • Medullo, Pinealo, Ependymo-
  • Atypical teratoid / rhabdoid tumour

WHO Grade 1 astrocytoma (non-infiltrative or Localised).

Children and young adults.

Discrete borders. Well circumscribed. Benign. Cystic with Mural nodule +.

Site: Third ventricle, optic nerve, spinal core and cerebrum.

MAP kinase pathway alterations. Eg: KIAA1549-BRAF fusion.

No IDH mutation in WHO grade I astrocytoma (only for grade II and III).

Microscopy

  • Bipolar cells with hair like process
  • Fibrillary / Microcystic stroma
  • Rosenthal fibres – Eosinophilic corkscrew structures.
  • Mulbery-like inclusions – Eosinophilic granular bodies.

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