Multifocal neurological involvement as the only manifestation of IgG4-related disease.

A 46-year-old man with progressive visual loss underwent brain MRI showing
multifocal nodular pachymeningeal thickening involving optic nerve meninges
bilaterally and internal acoustic meatus dura mater (Figure 1). Diffuse
meningiomatosis was diagnosed and radiation therapy was given with symptom
stabilization. Four years later left hearing loss and right hypoacusia occurred,
with slight transient improvement after high-dose dexamethasone. Serum IgG4 was
increased. CSF analysis showed increased protein, oligoclonal IgG, plasma cells, and
lymphocytes. Cerebral biopsy showed meningeal plasma-cell granuloma with IgG4-
positive polyclonal plasma-cells and B-lymphocyte infiltration (Figure 2). IgG4-
Related-Disease was diagnosed.1 Rituximab was unsuccessful. IgG4-Related-Disease is
a fibroinflammatory multi-organ condition characterized by tumefactive lesions and
lymphoplasmacytic infiltrates rich in IgG4-positive plasma-cells that may affect
every organ; serum IgG4 may be elevated. Although IgG4-Related-Disease with
exclusive multifocal central nervous system localization is extremely rare and often
misdiagnosed,2-4 it should be considered in the differential diagnosis of tumor-like
intracranial lesions and hyperthrophic pachymeningitis.