Brain histopathological study and prognosis in MOG antibody-associated demyelinating pseudotumor

Abstract

Our objective was to examine the brain biopsies by histopathology and investigate the prognosis of patients with myelin oligodendrocyte glycoprotein antibody-associated demyelinating pseudotumor. The clinical, MRI, and histological features of two patients with myelin oligodendrocyte glycoprotein antibody-associated demyelinating pseudotumor were reviewed. Both patients were treated with steroid plus rituximab and followed up. The brain biopsies of both cases revealed T cells, macrophages, and complement-mediated demyelination, which was in accord with multiple sclerosis-like pathology. Moreover, both cases showed favorable response to steroid plus rituximab therapy. Our cases add a new variant to the myelin oligodendrocyte glycoprotein-encephalomyelitis spectrum, which favorably responds to immunotherapy.

Figure 1

(A–C) Case 1 MRI findings showed large white matter lesions with patchy Gd‐enhancement located in the right frontal lobe and basal ganglia region. (A) axial‐fluid‐attenuated inversion recovery (FLAIR), (B), Gd‐enhanced axial T1, and the lesion obviously regressed during follow‐up (C, axial‐FLAIR). (D–I) Case 2 MRI showed a large edematous lesion in the white matter of the right frontal lobe and periventricular zone with linear Gd‐enhancement (D, axial‐FLAIR, E, Gd‐enhanced axial T1) that had regressed on follow‐up at 3 months (F, axial‐FLAIR). (G–I) One year later another large edematous lesion was seen in the left basal ganglia region with patchy enhancement (G, axial‐FLAIR, H, Gd‐enhanced axial T1) that regressed during follow‐up (I, axial‐FLAIR).

Figure 2

In Case 1 and Case 2, both of the right frontal lobe lesions revealed extensive inflammatory cells (HE). Perivascular and parenchymal CD4⁺ and CD8⁺ T cells dominated the inflammation, with many active macrophages (CD163⁺). However, there was a single CD20⁺ B cells in the lesions of case 1 and a few CD20⁺ B cells in the lesions of Case 2. A marked demyelinating lesion (LFB), loss of MOG immunoreactivity, a decrease of AQP4 expression and reactive GFAP ⁺ astrocytes, and mild complement deposition (C9neo, red arrows) were also seen in the lesion. There were scattered Ki67⁺ cells, few cells expressed p53 or Olig‐2 proteins, and none that expressed IDH1 protein were detected in the lesions of the two cases. HE, hematoxylin and eosin; LFB, luxol fast blue; MOG, myelin oligodendrocyte glycoprotein; AQP4, aquaporin‐4; GFAP, glial fibrillary acidic protein; IDH1, isocitrate dehydrogenase 1. Magnification: HE, CD4, CD8, CD163, CD20, LFB, MOG, Ki67⁺, p53, Olig‐2, IDH1 × 200; AQP4, GFAP, C9neo × 400.