PMC3640227_01
(a) T1 axial with gadolinium at presentation, (b) T1 axial at 2 months, (c) T1 axial 9 months postdiagnosis, (d) H and E, x 40 - Granulomatous inflammation, (e) CD68 (x 40) diffuse positive reaction for histiocytes, (f) CD3 x 40 stain positive for T lymphocytes
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F1
Magnetic resonance imaging [Figure 1a] revealed a solitary 27 x 22 mm enhancing right parafalcine lesion with surrounding edema and mass effect causing compression of the right lateral ventricle. Histopathological examination of the stereotactic biopsies [Figure 1d] showed white matter with diffuse foamy- or rod-shaped cells forming an occasional cluster, a few scattered bizarre gemistocytic astrocytes, and round cells. Immunohistochemistry showed a diffuse population of CD68-positive macrophages and histiocytes forming focal dense clusters and aggregate [Figure 1e]. These were surrounded by a dense population of CD3-positive T-cells [Figure 1f]. Follow-up imaging at 2 months [Figure 1b] revealed a decrease in the size of the lesion, and by 8 months the lesion had completely resolved [Figure 1c].