Immunoglobulin G4-related Lung Disease: CT Findings with Pathologic Correlations

Purpose: To retrospectively analyze radiologic findings of immunoglobulin G4 (IgG4)-related lung disease as correlated with pathologic specimens. Materials and Methods: This study was approved by the institutional review board, and all patients had consented to the use of their medical records for the purpose of research. This study included 13 patients with IgG4-related lung disease (nine men and four women; age range, 43-76 years). Computed tomographic (CT) findings were retrospectively analyzed with regard to the characteristics, shape, and distribution of the radiologic findings and were correlated with surgically resected or biopsy lung specimens in seven patients. Statistical analysis was not used in this study. Results: On the basis of the predominant radiologic abnormality, IgG4- related lung disease could be categorized into four major subtypes: solid nodular type having a solitary nodular lesion that included a mass (four patients); roundshaped ground-glass opacity (GGO) type characterized by multiple round-shaped GGOs (two patients); alveolar interstitial type showing honeycombing, bronchiectasis, and diffuse GGO (two patients); and bronchovascular type showing thickening of bronchovascular bundles and interlobular septa (five patients). Pathologically, solitary nodular lesions consisted of diffuse lymphoplasmacytic infiltration with fibrosis. Thickened bronchovascular bundles or interlobular septa and GGO on CT images pathologically corresponded to lymphoplasmacytic infiltration and fibrosis in peribronchiolar or interlobular interstitium and alveolar interstitium, respectively. The radiologic findings of honeycombing corresponded to disrupted alveolar structures and dilated peripleural air spaces. Conclusion: IgG4- related lung disease manifested as four major categories of CT features. Pathologically, these features corresponded to IgG4- related sclerosing inflammation along the intrapulmonary connective tissue. (C) RSNA, 2009