Immunoglobulin G4-related hypertrophic pachymeningitis with an isolated scalp mass mimicking a brain tumor: a case report and literature review

Abstract

Immunoglobulin G4-related disease (IgG4-RD) is an autoimmune disorder associated with fibroinflammatory conditions that can affect multiple organs. Hallmark histopathological findings of IgG4-RD include lymphocytic infiltration of IgG4-positive plasma cells, storiform fibrosis, and obliterative phlebitis. However, little is known about central nervous system involvement of IgG4-RD. Hypertrophic pachymeningitis (HP) has recently been reported as a manifestation of IgG4-RD, which may have previously been demonstrated in a significant percentage of idiopathic cases. Herein, we report a rare case of a 63-year-old male who presented with a scalp mass that mimicked a brain tumor. He was diagnosed with IgG4-related HP (IgG4-RP) after surgery. This case suggests that awareness of a possibility of IgG4-RP in patients with isolated scalp masses, even in the absence of systemic symptoms, is crucial. A combination of careful history taking, evaluation of serum IgG4-levels and imaging as an initial work-up, followed by tissue biopsy, is important for the differential diagnosis of IgG4-RP, malignancy, and other infectious diseases.

Keywords: Brain neoplasms; Hypertrophic pachymeningitis; Immunoglobulin G4-related disease; Immunoglobulin G4-related pachymenigitis.

Figure 1

Brain magnetic resonance imaging of preoperation shows an enhanced extraaxial mass-like lesion with adjacent subgaleal tissue thickening/enhancement, bony destruction in the right frontal area, dural thickening/enhancement, and leptomeningeal enhancement along the right cerebral convexity. (A) T2-axial, (B) precontrast T1-axial, and (C) postcontrast T1-axial images.

Figure 2

Histopathologic findings of tissue biopsy from scalp lesion. (A) Storiform fibrosis (yellow arrow) with destruction of the skull on H&E stain (×100). (B) Dense fibrosis and infiltration of inflammatory cells including lymphocytes, plasma cells and histiocytes on H&E stain (×200). (C) Increased immunoglobulin G4-positive cells (up to 68/high power field on immunoglobulin G4 immunohistochemistry stain) (×200).

Figure 3

Serial changes of serum acute phase reactants according to time. (A) Erythrocyte sedimentation rate (mm/h); (B) C-reactive protein (mg/dL). POD: postoperation day.