CNS tumor
Meningeal tumors
Atypical meningioma
Revised: 2 January 2018, last major update January 2014
Copyright: (c) 2002-2017, PathologyOutlines.com, Inc.
PubMed Search: Atypical meningioma [title]
Meningeal tumors
Atypical meningioma
Topic Completed: 1 January 2014
Minor changes: 12 December 2019
Revised: 2 January 2018, last major update January 2014
Copyright: (c) 2002-2017, PathologyOutlines.com, Inc.
PubMed Search: Atypical meningioma [title]
Table of Contents
Definition / general | Radiology images | Case reports | Treatment | Gross description | Microscopic (histologic) description | Microscopic (histologic) images | Cytology description | Cytology images | Positive stains | Negative stains | Differential diagnosis | Additional referencesCite this page: Kresak, J. Atypical meningioma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/cnstumoratypicalmeningioma.html. Accessed May 30th, 2020.
Definition / general
- WHO grade II
- 5 - 15% of meningiomas
- Diagnostic criteria either:
- 4 - 19 mitotic figures/10 HPF OR
- Brain invasion OR
- Three of these histologic features:
- Increased cellularity
- Small cells with high N/C ratio
- Large and prominent nucleoli
- Patternless or sheet-like growth (loss of lobular architecture)
- Foci of "spontaneous" or geographic necrosis
- Note:
- Invasion of dura, bone or soft tissue does not affect grading
- Pleomorphic or atypical nuclei do not affect grade
- Ki67 is not a true diagnostic criteria, however it is usually greater than 4% and up to 20%
- May be associated with prior irradiation (J Neurosurg 2004;100:488)
- 29% recur (vs. 9% of classic meningiomas and 50% of anaplastic meningiomas)
- 10 year survival is 79% but 26% will assume a malignant phenotype
- In one study, cyclin A and topoisomerase II staining predicted recurrence (Arch Pathol Lab Med 2002;126:1079)
Radiology images
Images hosted on other servers:
Atypical meningioma with surrounding edema
Primary lesion in left nasal cavity
T1 weighted MRI
Case reports
- 36 and 70 year old women with optic nerve seeding of atypical meningiomas presenting with subacute visual loss (J Neurosurg 2013;119:494)
- 44 year old man with atypical primary meningioma in the nasal septum with malignant transformation and distant metastasis (BMC Cancer 2012;12:275)
- Elderly man with metastatic atypical meningioma (J Clin Neurosci 2000;7:69)
Treatment
- Gross total resection
- Postsurgical radiation is often offered for atypical meningiomas, especially after a subtotal resection (J Neurooncol 2013;115:241)
- Stereotactic radiosurgery
Gross description
- Dural based
- May be well circumscribed or focally adherent to brain parenchyma
- Size can vary widely
Microscopic (histologic) description
- May have identical histology to any grade I variant meningioma yet contain increased mitoses (4 - 19/10 HPFs)
- May have increased cellularity or areas of small cell collections
- May have sheet-like growth pattern
- May have areas of spontaneous necrosis
- May have macronucleoli
Microscopic (histologic) images
Images hosted on other servers:
Tumor cells with macronucleoli
Sheet-like growth pattern
Increased mitotic figures
Increased Ki67 (MIB1) proliferation index
PHH3 highlights mitotic figures
Brain invasion - no clear arachnoid plane
Bone invasion
Nests of cohesive, meningothelial cells
Whorl formation
Micronecrosis
Sheet-like (syncytial) growth
H&E, EMA and vimentin
H&E
Cytology description
- Squash prep shows similar histology as standard meningioma but may also show occasional mitoses or macronucleoli
Cytology images
Images hosted on other servers:
Meningothelial cells and whorl
Positive stains
- EMA
- Progesterone receptor (up to 85%) (J Clin Neurosci 2014;21:421)
Negative stains
Differential diagnosis
- Hemangiopericytoma
- Malignant meningioma with mitoses greater than 20/10 HPF
- Meningioma with atypical features insufficient for criteria above
- Necrosis due to prior therapy (which is not considered spontaneous)
Additional references
