Immunoglobulin G4-Related Disease Unilaterally Involving the Pulmonary Interstitium and Pleura: A Case Report

Immunoglobulin G4-related disease is a novel inflammatory entity involving multiple organs of the body. In the lungs, it is accompanied by infiltration of IgG4-positive lymphocytes and increased serum levels of IgG4. Previous studies have reported radiological findings of IgG4-related lung disease in the pulmonary parenchyma; however, there are few case reports of pleural involvement. Here, we report the case of a 66-year-old man with IgG4-related disease unilaterally involving the lung interstitium and pleura. Thoracic computed tomography images demonstrated pleural effusion and thickening resembling a primary or secondary pleural malignancy. The diagnosis of IgG4-related disease was confirmed by video-assisted-thoracoscopic biopsy. This rare disease should not be overlooked in patients with radiological findings that are suggestive of pleural malignancies.