IgG4-related interstitial lung disease: a new and evolving concept

Purpose of review This review examines recent advances in our knowledge of the clinical, pathological, diagnostic, and therapeutic aspects of IgG4-related interstitial lung disease (ILD). Recent findings A recent case series of ILD with IgG4-positive plasma cells suggested grade 1 lymphomatoid granulomatosis. The presence of the IgG4-positive plasma cells with the lack of atypical cells favored IgG4-related ILD as a diagnosis. In another case study, four out of 30 patients with autoimmune pancreatitis developed pulmonary involvement during follow-up. Elevations of IgG4 and Krebs von den Lungen-6 levels were associated and thought to be predictive of the development of IgG4-related lung disease. A retrospective analysis investigating radiological/pathologic correlation in IgG4 lung disease identified computed tomographic features pathologically corresponding to IgG4-related sclerosing inflammation in the pulmonary interstitium. Summary IgG4-related ILD is a new and evolving entity. It can occur with or without systemic involvement. Larger studies are necessary to elucidate the exact mechanism and clinical characteristics of this disorder.