IgG4 Related Diseases

**73**

**Table 1.**



muscles and orbit - retroperitoneal space


**Chapter 5**

**Abstract**

Rheumatology

**1. Spectrum of IgG4-related disease**

IgG4-Related Disease and

the Spectrum of Mimics in

*Agata Sebastian, Piotr Donizy and Piotr Wiland*

Immunoglobulin G4 (IgG4)-related disease (IgG4-RD) is an immune-mediated condition that can affect almost any organ. It is a chronic, systemic, inflammatory condition of unknown etiology. Pseudotumor formation is the most common and characteristic clinical symptom. The variable organ dysfunction reflects the clinical presentation. Because there are not specific antibodies for this disease, histopathological assessment provide the pivotal role in the diagnosis. IgG4-RD is characterized by a lymphoplasmacytic infiltrate composed of IgG4+ plasma cells, storiform fibrosis, obliterative phlebitis and mild to moderate eosinophilia. In this chapter we present the newest knowledge of the IgG4-RD pathogenesis and then concentrate on clinical symptoms which can mimic many other conditions in rheumatology, e.g., this common as Sjӧgren syndrome or rare as vasculitis or idiopathic retroperitoneal fibrosis.

**Keywords:** IgG4-related disease, Mikulicz syndrome, Kuttner's disease, pseudotumor

IgG4-related disease (IgG4-RD) belongs to quite new disease entities; its name

dacryoadenitis



was introduced in the 21st century. In the course of the disease, characteristic infiltrates are formed, composed of mononuclear cells, mainly IgG4 cells. Also, fibrosis of affected organs is observed. In the majority of patients, concomitant increase in serum IgG4 concentration is found, but not in every patient [1, 2].

**Location of lesions Name of IgG-RD disease**

*Current nomenclature of most common clinical forms of IgG4-RD.*
