Letter re: Teaching NeuroImages: Idiopathic hypertrophic pachymeningitis

As alluded to by Drs. Wasilewski and Samkoff,1 immunoglobulin G4 (IgG4)–related disease (RD) is an increasingly recognized cause of hypertrophic pachymeningitis (HP) and likely accounts for a substantial subset of cases previously thought to be idiopathic.2 Although normal IgG4 levels in serum and CSF argue against IgG4-related HP in this case, meningeal biopsy remains the diagnostic gold standard.3,4 Since IgG4-RD is a major consideration, it is of critical importance to immunostain biopsied tissue for the number of IgG4+ cells/high-powered field (HPF) prior to labeling the disease entity idiopathic; more than 10 IgG4+ cells/HPF suggests IgG4-related HP.4 Although both IgG4-related and idiopathic HP are inflammatory steroid-responsive illnesses, differentiation permits better understanding of individual disease mechanisms and may greatly help guide decision-making when selecting second-line therapies in treatment-resistant cases, such as the use of rituximab in refractory IgG4-related HP.5

Source: Neurology - June 5, 2017 Category: Neurology Authors: Budhram, A. Tags: WRITECLICK & amp;reg; EDITOR ' S CHOICE Source Type: research