Coincidence of Mixed Connective Tissue Disease with Immunoglobulin G4–Related Disease: A Case Report

Immunoglobulin G4–related disease (IgG4-RD) is an immune-mediated fibroinflammatory disorder characterized by mass forming lesions that can result in irreversible organ damage and mortality if ignored. Mixed connective tissue disease (MCTD) is characterized as an overlap of systemic lupus erythematosus (SLE), systemic sclerosis, inflammatory myopathy, and rheumatoid arthritis (RA). While cases of IgG4-RD linked to SLE and RA have been documented, to the authors’ knowledge, there has not been a recorded instance of a patient with IgG4-RD related with MCTD. A patient diagnosed with both MCTD and IgG4-RD is presented.

Cite this article as: Kocaayan H, Ediboglu ED, Aydin I, Erdogan N, Akar S. Coincidence of mixed connective tissue disease with immunoglobulin –related disease: A case report. Eur J Rheumatol. 2025, 12 (4), 0043, doi: 10.5152/ eurjrheum.2025.25043.