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Novel histopathological classification of meningiomas based on dural invasion
Makoto Murase1, Ryota Tamura1, Yuki Kuranari1
1Department of Neurosurgery, Keio University School of Medicine, Shinjuku-ku, Tokyo, Japan.
Aims:
Histological invasion into the adjacent brain parenchyma is frequently investigated in meningioma because it is an important morphological criterion for grade II meningioma according to the 2016 WHO classification. However, few studies have focused on dural invasion of meningiomas. Herein, we propose a novel histopathological classification based on dural invasion of meningiomas.
Methods:
Forty-nine cases with WHO grade I meningiomas who underwent Simpson grade I removal were collected. After the meningeal layer (ML) and periosteal layer (PL) of dura mater were visualised by Masson's trichrome stain, we evaluated the depth (to the ML and PL) and the patterns (1, expanding; 2, infiltrating) of dural invasion of meningiomas using serial paraffin sections. Invasion-associated markers, including Ki-67, matrix metalloproteinase (MMP)-1, MMP-9 and MMP-13, aquaporin 1 and Na-K-2Cl cotransporter, were quantitatively analysed by immunohistochemistry.
Results:
Thirty-five cases (71.4%) showed the dural invasion. In 27 of these 35 cases (77.1%), dural invasion was localised in ML. Type 1 (expanding type) and type 2 (infiltrating type) invasions were observed in 23 and 12 cases, respectively. The recurrence rate in cases with type 2 invasion was significantly higher than that in cases with type 1 invasion. The percentage of MMP-1-positive tumour cells was also significantly higher in cases with dural invasion than those without, suggesting involvement of MMP-1 in dural invasion.
Conclusions:
We quantitatively evaluated the depth and patterns of dural invasion in meningiomas. The patterns of dural invasion were associated with meningioma recurrence.
Insights
Meningioma dural invasion patterns, specifically infiltrating types, correlate with higher recurrence rates. This study introduces a novel classification for meningioma dural invasion, highlighting matrix metalloproteinase-1
Area of Science:
- Neurosurgery
- Pathology
- Oncology
Background:
- Meningiomas are tumors arising from the meninges.
- Dural invasion is a key factor in meningioma grading and prognosis.
- Current classifications primarily focus on parenchymal invasion, with less emphasis on dural invasion patterns.
Purpose of the Study:
- To propose and validate a novel histopathological classification system for meningioma dural invasion.
- To investigate the relationship between dural invasion patterns and meningioma recurrence.
- To analyze the expression of invasion-associated markers in relation to dural invasion.
Main Methods:
- Analysis of 49 WHO grade I meningiomas with Simpson grade I resection.
- Histopathological evaluation of dural invasion depth (meningeal layer, periosteal layer) and patterns (expanding vs. infiltrating) using Masson's trichrome stain.
- Quantitative immunohistochemical analysis of markers including Ki-67, MMP-1, MMP-9, MMP-13, aquaporin 1, and Na-K-2Cl cotransporter.
Main Results:
- Dural invasion was present in 71.4% of cases, predominantly within the meningeal layer (77.1%).
- Infiltrating (Type 2) dural invasion showed a significantly higher recurrence rate compared to expanding (Type 1) invasion.
- Elevated MMP-1 expression was associated with the presence of dural invasion.
Conclusions:
- A novel classification for meningioma dural invasion based on depth and pattern is proposed.
- The pattern of dural invasion is a significant predictor of meningioma recurrence.
- MMP-1 may play a role in the process of dural invasion in meningiomas.
