IgG4-Related Intracranial Hypertrophic Pachymeningitis : A Case Report and Review of the Literature

Abstract

Hypertrophic pachymeningitis is an uncommon disorder that causes a localized or diffuse thickening of the dura mater. Recently, the possibility that IgG4-related sclerosing disease may underlie some cases of intracranial hypertrophic pachymeningitis has been suggested. We herein report the tenth case of IgG4-related intracranial hypertrophic pachymeningitis and review the previous literature. A 45-year-old male presented with left-sided focal seizures with generalization. Magnetic resonance imaging (MRI) revealed a diffuse thickening and enhancement of the right convexity dura matter and falx with focal nodularity. The surgically resected specimens exhibited the proliferation of fibroblast-like spindle cells and an infiltration of mononuclear cells, including predominantly plasma cells. The ratio of IgG4-positive plasma cells to the overall IgG-positive cells was 45% in the area containing the highest infiltration of plasma cells. On the basis of the above findings, IgG4-related sclerosing disease arising from the dura mater was suspected. IgG4-related sclerosing disease should be added to the pachymeningitis spectrum.

Keywords: IgG4-related disease; Immunohistochemistry; MRI; Pachymeningitis.

Fig. 1

Preoperative axial (A), coronal (B), and sagittal (C) gadolinium-enhanced magnetic resonance images show irregular thickening and a marked enhancement of the right parieto-occipital dura and falx.

Fig. 2

Pathological findings. A : A macroscopic observation shows a solid yellow to white-colored lesion in the dura mater. B : The photomicrograph shows the solid lesion consisting of the proliferation of fibroblast-like spindle cells and an infiltration of mononuclear cells, including predominantly plasma cells, with abundant collagenous tissue (H&E; original magnification, ×400). C and D : IgG (C) and IgG4 (D) staining reveal that most of the plasma cells infiltrating into the sclerosing lesion are IgG-positive (IgG4-positive plasma cells/high power field, 78), and that the ratio of IgG4-positive plasma cells to the overall IgG-positive cells is 45% in the area containing the highest infiltration of plasma cells (original magnification, ×400).

Fig. 3

The twelve-month postoperative axial (A), coronal (B), and sagittal (C) gadolinium-enhanced magnetic resonance images show the disappearance of the mass in the convexity dural region. The mass adjacent to the superior sagittal sinus and falx is left in place.