A case of immunoglobulin G4-related lung disease with normal serum immunoglobulin G4 level and hybrid radiological findings

Abstract

Pulmonary involvement in immunoglobulin (Ig) G4-related disease is very rare and usually in the form of parenchymal infiltrates. Symptoms vary according to the location and severity of the infiltration. Previously, the radiological findings were categorized as solid nodule or mass, ground-glass opacity, interlobular septal, or bronchovascular bundle thickening. However, in some patients, all forms of radiological findings present at the same time. We do not know whether it is a type of disease or whether there is a difference in the disease course. Here, we present a patient, with normal serum IgG4 level, acute-subacute respiratory symptoms, extensive parenchymal consolidation in chest computed tomography, and intensive IgG4-positive-lymphoplasmocytic-infiltration in lung biopsy and the result of 6-month methylprednisolone and methotrexate treatment for IgG4-related lung disease.