IgG4 levels and plasmablasts as a marker for IgG4-related disease (IgG4-RD)

Stone and his coworkers present two elegant papers on IgG4-related disease (IgG4-RD).1 In ‘The Diagnostic Utility of Serum IgG4 Concentrations in IgG4-Related Disease’, Carruthers et al 2 retrospectively analysed charts of 190 patients with elevation of IgG4. They also randomly selected 3360 charts with normal IgG4 levels and reviewed 190 cases for characteristics of IgG4-RD. They found: In a closely related study by the same group, Wallace et al describe the ‘Diagnostic Utility of Plasmablasts as a Biomarker for IgG4 Related Disease (IgG4 RD) Independent of Serum IgG4 Levels’. Since we see patients with possible IgG4-RD in a variety of organs (table 1) that are often not easy to biopsy, serum IgG4 levels have incorrectly become a ‘surrogate’ marker for IgG4-RD in clinical practice.3 ,4 These articles will make us take a hard look at our current diagnostic approach to IgG4-RD. View this table: Table 1 IgG4-Related Diseases (IgG4-RD) are a Family Immuno-proliferative Disorders View this table: Table 2 Diagnostic criteria for IgG4-Related Disease The spectrum of IgG4-RD is remarkably complex (table 1) and it would be nice to simply think of this complex multisystem pathology as a single pathogenetic disorder occurring in a variety of target organs. Unfortunately, it may not be that simple. In a critical evaluation of the evolving …