Quiz on IgG4RD

In IgG4-related disease, IgG4+ plasma cells may be increased and distributed in various organs causing IgG4+ plasma cell infiltration. This can cause dense Lymphoplasmacytic inflammatory infiltration with increased numbers of IgG4+ plasma cells and often increased eosinophils; fibrotic collagen deposition containing fibroblasts and myofibroblasts known as a Storiform pattern of fibrosis; inflammatory infiltration in the walls and lumina of the veins identified as Obliterative phlebitis.

Reference - Floreani A, Okazaki K, Uchida K, Gershwin ME. IgG4-related disease: Changing epidemiology and new thoughts on a multisystem disease. J Transl Autoimmun. 2020;4:100074. Published 2020 Dec 19.

The diagnosis of IgG4- related disease is considered definite if all three criteria are met, and probable if the organ enlargement, mass or nodular lesions, or organ dysfunction and infiltration of IgG4+ cells (>10 cells/high power field (HPF) and IgG4+/IgG+ cell ratio >40%. cri¬teria are met, and possible if the organ enlargement, mass or nodular lesions, organ dysfunction, and increased serum IgG4 concentration >135 mg/dl criteria are met.

Reference - Floreani A, Okazaki K, Uchida K, Gershwin ME. IgG4-related disease: Changing epidemiology and new thoughts on a multisystem disease. J Transl Autoimmun. 2020;4:100074. Published 2020 Dec 19.

Increased infiltration of inducible-memory T regulatory cells (Tregs) in affected tissue and blood, with upregulation of IL-10 and tumor growth factor-β (TGF-β), has been observed in patients with IgG4-RD. TGF-β production from Tregs may stimulate fibroblasts causing fibrogenesis.

References - Floreani A, Okazaki K, Uchida K, Gershwin ME. IgG4-related disease: Changing epidemiology and new thoughts on a multisystem disease. J Transl Autoimmun. 2020;4:100074. Published 2020 Dec 19