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Clinico-pathological investigations of Rasmussen encephalitis suggest multifocal disease progression and associated focal cortical dysplasia Volume 15, numéro 1, March 2013



Figure 1 Presentation of Case 2, a 3.5-year-old boy with a two-year history of intractable seizures. Serial axial MRI depicting progressive focal cerebral atrophy 13 months (A and B) and 21 months (C and D) after the first seizure. T2-weighted (A) and Flair (B) revealed signal abnormalities in the posterior right insular lobe. T2 (C) and Flair (D) showed progressive deterioration of signal abnormalities involving the right insular and right frontal lobe. (E) Macroscopic surgical specimen. Serial axial T2-weighted MRI three months (F) and 4 months (G) after modified anatomical hemispherectomy depicting enlargement of the remaining left hemisphere and maintenance of the extradural cavity.



Figure 2 Presentation of Case 7, a 4-year-old boy with a one-year history of intractable seizures. Axial MRI depicts progressive, asymmetrically distributed, sulcal prominence with marked focal atrophy involving the right frontal lobe six months (A), nine months (B and C) and 14 months (D) after the first seizure; T2-weighted images (A, C, D) and T1-weighted images (B). PET images (E) also revealed prominent right hemispheric hypometabolism, which corresponded to marked frontal lobe atrophy visible on the surgical specimen in (F) (indicated by arrows).



Figure 3 Histopathological hallmarks of Rasmussen encephalitis. Immunohistochemical staining confirmed nodular infiltration of CNS tissue with T lymphocytes (A and C). These cells were mostly characterised as CD3 and CD8 positive cytotoxic killer cells attacking neurons. (B) CD20 staining labelled only few B lymphocytes within inflammatory nodules. (D) CD68 staining revealed the typical formation of microglial nodules in affected cortical areas. Scale bars: 100 Î¼m.



Figure 4 Histopathological stages of neuropathological patterns in RE (H and E staining). (A) Stage 1 was characterised by multifocal distribution of inflammatory changes (arrows); scale bar: 200 Î¼m (applies also to C). (B) In stage 3, severe neuronal loss and astroglial reaction occurred together with brain inflammation (arrow); scale bar: 500 Î¼m. (C) Stage 4 was characterised by prominent cortical atrophy with neuronal loss and astrogliosis. Extensive cortical vacuolation (arrow) was always visible and indicative of this stage.



Figure 5 Associated FCD type IIId (ILAE classification 2011). (A and B) Cortex without inflammatory changes (stage 0) revealed FCD with abnormal radial architecture and blurred grey-white matter boundary in Case 7; (A) H and E staining and (B) NeuN staining. (C and D) Cortex with discrete foci of inflammation but no evidence for gross neuronal injury (stage 1) revealed FCD with lack of tangential laminar organisation in Case 2; (C) H and E staining and (D) NeuN staining. Scale bars: 100 Î¼m.



Figure 6 Neuropathological examination of the hippocampal formation in RE patients. (A) Macroscopic examination of surgical hippocampus specimen and serial sections along the anterior-posterior axis revealed no abnormalities (scale in mm). (B and D) Microscopic inspection revealed inflammatory changes, neuronal cell loss, and astrogliosis in CA4, which is compatible with HS type 3 end folium sclerosis. (B, C and E) H and E staining. (D) GFAP staining. Scale bar in (B) is 500 Î¼m (applies also to D) and (E) 200 Î¼m (applies also to C). Data taken from Case 2.