BACKGROUNDImmunoglobulin G4-related disease (IgG4-RD) is a newly recognized systemic disease that can involve multiple organs and various clinical phenotypes. The purpose of this study was to analyze different types of organ involvement in IgG4-RD patients in China.

METHODSWe conducted a prospective cohort study on IgG4-RD patients to analyze the clinical manifestations and rare features of IgG4-RD. Patients were grouped into different types according to organ involvement regarding organ number and organ site. The constituent ratio in different types was also analyzed.

RESULTSA total of 200 IgG4-RD patients, with a male:female ratio of 2.08:1, were grouped into different types. Cases having involvement of two or three organs were the most common whereas the fewest number of patients had multi-organ (≥4) involvement. Serum IgG4 and IgE levels, IgG4/IgG ratio, and percentage of eosinophils increased as the number of involved organs increased. In addition, constituent ratio analysis revealed that patients with salivary gland/lacrimal gland swelling, who also constituted the largest number of IgG4-RD patients, had higher serum IgG4 concentrations and IgG4/IgG values, had higher percentage of Eos, and were more likely to have had a history of allergies relative to patients with internal organ involvement.

CONCLUSIONSThe characteristic feature of IgG4-RD is multiple organ involvement with various clinical manifestations and different types. Although serum IgG4 levels increased with the number of involved organs, serum IgG4 levels were higher for those patients with salivary gland/lacrimal gland swelling compared with those with internal organ involvement. Thus, valuable clues to the differential diagnosis of IgG4-RD could be obtained by examining the clinical patterns of organ involvement.