대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

IgG4-related lung disease

Radiologic Findings

Chest x-ray showed multiple patchy opacities in middle and lower lung zones. Initial chest CT demonstrated bilateral subpleural consolidations with cavitary changes in both the lower lobes. Surrounding GGO and bronchiectasis were also observed. A follow-up chest CT taken 3 months later showed increased extent of cavitary consolidations. They showed a strong FDG uptake (maximum SUV, 11.2) on PET-CT scan. Percutaneous lung biopsy was performed for each cavitary lesion, subsequently having identical histologic findings. The pathologic features showed a heavy lymphoplasmacytic infiltration and fibrosis. Immunostaining of IgG4 revealed abundant IgG4-positive plasma cells in the specimen. Serum IgG4 level was elevated up to 204mg/dL, it was turned out to be IgG4-related lung disease. A follow-up CT scan after medication with prednisone showed that the extent of the disease was markedly decreased.

CT after medication with prednisolone

Brief Review

IgG4-related disease is a systemic fibro-inflammatory disease characterized by extensive IgG4-positive plasma cell infiltration of various organs. Patterns of IgG4-related disease involving thoracic organs have been classified as parenchymal, airway, pleural and mediastinal involvements.
Based on CT features, Inoue et al. categorized IgG4-related lung into four subtypes: solid nodular type, round-shaped GGO type, alveolar interstitial type, and bronchovascular type. IgG4-related lung diseases should be differentiated from a variety of lung disease, including neoplastic and non-neoplastic lesions. Solid nodular and round-shaped GGO lesions can mimic a primary lung cancer. The differential diagnosis of bronchovascular-type includes lymphoproliferative disorders such as multicentric Castleman disease, sarcoidosis, and lymphangitis carcinomatosis. Alveolar interstitial-type lesion radiologically resembles a nonspecific interstitial pneumonia.
Serum IgG4 level was elevated in the majority of patients with IgG4-related lung disease, and pathologically it is characterized by diffuse lymphoplasmacytic infiltration, fibrosis, and positive for IgG4 immunostaining. Intrathoracic IgG4-related disease generally responds well to steroid treatment, but azathioprine, methotrexate or rituximab therapy could be applied to steroid-resistant IgG4-related lung disease.

References

1. D. Inoue, Y. Zen, H. Abo,T. Gabata, H. Demachi, T. Kobayashi, et al. Immunoglobulin G4 related lung disease: CT findings with pathologic correlations. Radiology 2009; 251: 260-270.
2. J.H. Ryu, H. Sekiguchi and E.S. Yi Pulmonary manifestations of immunoglobulin G4-related sclerosing disease. EurRespir J 2012; 39: 180-186
3. S.Matsui, A. Hebisawa, F. Sakai, H. Yamamoto, Y. Terasaki, Y. Kurihara, et al. Immunoglobulin G4-related lung disease: Clinicoradiological and pathological features. Respirology 2013; 18, 480-487

Please refer to

Case 1015 Case 907 Case 723

Keywords

IgG4-related lung disease, IgG4-related sclerosing disease, Lung, Consolidation with cavity,