PMC3326948_01
(a) CT scan. Axial slice shows right frontal hypodense lesion without calcifications (white arrow). (b) Axial MRI. T1-weighted image reveals an isointense lesion (white arrows). (c) Axial MRI. T1-weighted image with contrast agent shows gyriform enhancing (arrowheads). (d) Axial MRI. FLAIR-weighted image shows a hyperintense signal
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F1
Magnetic resonance images (MRI) revealed an extensive parieto-occipital lesion and another right frontal lesion, initially suggestive of encephalitis [Figure 1].
Cerebral cortex. (a) Diffuse perivascular proliferation (arrows). HE, Objective x4. (b) Thickening of vascular wall and reduction of the lumen (L) by proliferation of perivascular, elongated, fibroblast-like cells (arrows). HE, Objective x40
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F2
The histopathologic diagnosis, complemented by immunohistochemical studies, was MA, characterized by diffuse proliferation of elongated perivascular, fibroblast-like cells in the cerebral cortex [Figure 2].
Cerebral cortex. Reactivity of the endothelium by anti-CD34, a marker for endothelial cells (arrows). Objective x40
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F3
Immunostaining of smooth muscle actin or epithelial membrane antigen in the perivascular cells was not observed; however, immunostaining of CD34, a marker for endothelial cells, was positive only in the endothelial cells that normally cover the intima [Figure 3].