Clinical characterization of 52 patients with immunoglobulin G4-related disease in a single tertiary center in Japan: Special reference to lung disease in thoracic high-resolution computed tomography.

•Serum levels of LDH, IgG, and soluble IL-2R are significantly higher in positive lung involvement than in negative patients.•The lung involvement in IgG4-related disease might be linked to a more intense inflammatory reaction.•The lung involvement patients have high occurrences of positive RF or hypocomplementemia.•IgG4-RD is associated with diverse thoracic CT findings and a decreased diffusion capacity.•Decreased diffusion capacity might reflect the activation of lymphocytes and/or plasma cells that accumulate in interstitium.