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Chordoid Meningioma: Differentiating a Rare World Health Organization Grade II Tumor from Other Meningioma Histologic
J B Pond1, T G Morgan2, K J Hatanpaa3
1From the Departments of Neuroradiology (J.B.P., T.G.M., Z.F.Y., D.B.M.) jasonbpond@gmail.com.
Background And Purpose:
Meningiomas are very commonly diagnosed intracranial primary neoplasms, of which the chordoid subtype is seldom encountered. Our aim was to retrospectively review preoperative MR imaging of intracranial chordoid meningiomas, a rare WHO grade II variant, in an effort to determine if there exist distinguishing MR imaging characteristics that can aid in differentiating this atypical variety from other meningioma subtypes.
Materials And Methods:
Ten cases of WHO grade II chordoid meningioma were diagnosed at our institution over an 11-year span, 8 of which had preoperative MR imaging available for review and were included in our analysis. Chordoid meningioma MR imaging characteristics, including ADC values and normalized ADC ratios, were compared with those of 80 consecutive cases of WHO grade I meningioma, 21 consecutive cases of nonchordoid WHO grade II meningioma, and 1 case of WHO grade III meningioma.
Results:
Preoperative MR imaging revealed no significant differences in size, location, signal characteristics, or contrast enhancement between chordoid meningiomas and other meningiomas. There were, however, clear differences in the ADC values and normalized ADC ratios, with a mean absolute ADC value of 1.62 ± 0.33 × 10(-3) mm(2)/s and a mean normalized ADC ratio of 2.22 ± 0.47 × 10(-3) mm(2)/s in chordoid meningiomas compared with mean ADC and normalized ADC values, respectively, of 0.88 ± 0.13 × 10(-3) mm(2)/s and 1.17 ± 0.16 × 10(-3) mm(2)/s in benign WHO grade I meningiomas, 0.84 ± 0.11 × 10(-3) mm(2)/s and 1.11 ± 0.15 × 10(-3) mm(2)/s in nonchordoid WHO grade II meningiomas, and 0.57 × 10(-3) mm(2)/s and 0.75 × 10(-3) mm(2)/s in the 1 WHO grade III meningioma.
Conclusions:
Chordoid meningiomas have statistically significant elevations of ADC and normalized ADC values when compared with all other WHO grade I, II, and III subtypes, which enables reliable preoperative prediction of this atypical histopathologic diagnosis.
Insights
Chordoid meningiomas, a rare subtype of meningioma, show significantly higher apparent diffusion coefficient (ADC) values on MRI. This finding aids in the preoperative diagnosis of this specific brain tumor variant.
Area of Science:
- Neurology
- Radiology
- Oncology
Background:
- Meningiomas are common primary intracranial neoplasms.
- Chordoid meningiomas represent a rare WHO grade II variant.
- Distinguishing chordoid meningiomas preoperatively is challenging.
Purpose of the Study:
- To identify distinguishing MR imaging characteristics of intracranial chordoid meningiomas.
- To differentiate chordoid meningiomas from other meningioma subtypes using preoperative MRI.
- To assess the utility of ADC values in diagnosing chordoid meningiomas.
Main Methods:
- Retrospective review of preoperative MR imaging in 8 chordoid meningiomas (WHO grade II).
- Comparison of ADC values and normalized ADC ratios with 80 WHO grade I, 21 nonchordoid WHO grade II, and 1 WHO grade III meningiomas.
- Analysis included size, location, signal characteristics, and contrast enhancement.
Main Results:
- No significant differences in size, location, signal, or enhancement were found between chordoid and other meningiomas.
- Chordoid meningiomas exhibited significantly higher mean absolute ADC values (1.62 ± 0.33 × 10⁻³ mm²/s) and normalized ADC ratios (2.22 ± 0.47 × 10⁻³ mm²/s).
- These values were markedly higher than those in WHO grade I, nonchordoid WHO grade II, and WHO grade III meningiomas.
Conclusions:
- Elevated ADC and normalized ADC values are statistically significant in chordoid meningiomas compared to other subtypes.
- These diffusion parameters enable reliable preoperative prediction of chordoid meningioma histopathology.
- MRI-based ADC measurements can aid in differentiating this rare meningioma variant.
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