World Health Organization (WHO) classification of meningioma

Subtypes of meningioma

Criteria for assigning CNS WHO grades 2 and 3

Meningothelial meningioma
Fibrous meningioma
Transitional meningioma
Psammomatous meningioma
Angiomatous meningioma
Microcystic meningioma
Secretory meningioma
Lymphoplasmacyte-rich meningioma
Metaplastic meningioma
Chordoid meningioma
Clear cell meningioma
Rhabdoid meningioma
Papillary meningioma
Atypical meningioma
Anaplastic (malignant) meningioma

Grade 2 (any of the following):

4 to 19 mitotic figures in 10 consecutive HPF of each 0.16 mm² (at least 2.5/mm²)
Unequivocal brain invasion (not only perivascular spread or indentation of brain without pial breach)
Specific morphologic subtype (chordoid or clear cell)
At least 3 of the following:
- Increased cellularity
- Small cells with high N:C ratio
- Prominent nucleoli
- Sheeting (uninterrupted patternless sheet-like growth)
- Foci of spontaneous (noniatrogenic) necrosis

Grade 3 (any of the following):

≥20 mitotic figures in 10 consecutive HPF of each 0.16 mm² (at least 2.5/mm²)
Frank anaplasia (sarcoma-, carcinoma-, or melanoma-like appearance)
TERT promoter mutation
Homozygous deletion of CDKN2A and/or CDKN2B

CDKN2A: cyclin-dependent kinase inhibitor 2A; CDKN2B: cyclin-dependent kinase inhibitor 2B; CNS: central nervous system; HPF: high-power field; TERT: telomerase reverse transcriptase; WHO: World Health Organization.

Adapted from Central Nervous System Tumours: WHO Classification of Tumours, 5th ed, Vol. 6, WHO Classification of Tumours Editorial Board, Meningioma, pages 284-7. Copyright © 2021 International Agency for Research on Cancer. https://publications.iarc.fr/Book-And-Report-Series/Who-Classification-Of-Tumours/Central-Nervous-System-Tumours-2021 (Accessed on April 26, 2024).

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World Health Organization (WHO) classification of meningioma