PMC4774166_01
Axial contrast-enhanced computed tomography (a), T1-weighted noncontrast (b) and T1-weighted contrasted (c) magnetic resonance imaging showing contrast-enhancing predominantly extra-axial dural-based lesion with invasion into underlying brain parenchyma. Two radiologic distinct components are delineated by the red arrow in the T1-weighted contrast-enhanced coronal and sagittal images (d and e)
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F1
Contrast-enhanced head computed tomography scan and subsequent brain magnetic resonance imaging with gadolinium demonstrated a large, multilobulated, contrast enhancing, dural-based, and predominantly extra-axial mass in the right parietooccipital region with apparent invasion of the underlying right parietal brain parenchyma [Figure 1].
Papillary meningioma (H and E, x40). This tumor was characterized by sheet-like growth pattern (a) high mitotic activity with more than 20 mitotic figures per 10 high-power fields (arrows) (b) forming focal papillary structures (c) and area of necrosis (d)
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F2
The sections that were submitted from the superficial dural-based lesion showed a predominantly solid growth pattern forming focal papillary structures [Figure 2]. Mitotic activity was high with more than 20 mitotic figures per 10 high-power fields [Figure 2]. Necrosis was focally present [Figure 2].
Anaplastic meningioma (H and E x40). This tumor was characterized by sheet-like growth pattern (a) high mitotic activity with more than 20 mitotic figures per 10 high-power fields (arrows) (b) better-differentiated area showed morphologic features of a transitional meningioma with psammoma bodies (c) and identifiable whorl formations (d)
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F3
The sections that were submitted from the deeper ventricular lesion showed a different morphology with features consistent with a transitional-type meningioma with identifiable whorl formations and psammoma bodies [Figure 3]. This lesion also showed more than 20 mitotic figures per 10 high-power fields [Figure 3], thus meeting the histologic features of anaplastic meningioma, WHO Grade III.
Strong epithelial membrane antigen positivity in both the anaplastic (a) and papillary (b) meningiomas (a and b: EMA IHC, x20)
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F4
By immunohistochemistry, both tumors showed an immunophenotype consistent with meningioma with strong positivity for epithelial membrane antigen [Figure 4] and vimentin.
Collision between the anaplastic (above) and papillary (below) meningiomas (a) H and E, x4. Cytokeratin AE1/AE3 is positive in the papillary meningioma and completely negative in the anaplastic meningioma; clearly delineating the two tumors (b) CK AE1/AE3 IHC x4, higher power x10 of the same area (inset)
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F5
The most striking difference, however, was the very strong immunoreactivity for cytokeratin (CK) AE1/AE3 [Figure 5] and CK8/18 that was seen only in the papillary meningioma and not in the anaplastic meningioma.