CT findings of IgG4-related thoracic disease: correlations with clinical and laboratory characteristics

<bold>Introduction:</bold> Thoracic involvement of IgG4-related disease (IgG4-RD) is relatively rare and its disease spectrum has not been fully described. This study aimed to analyze radiological abnormities and explore clinical and laboratory characteristics of IgG4-related thoracic disease in a large cohort. <bold>Methods:</bold> 232 IgG4-RD patients with thoracic involvement were retrospectively analyzed. The radiological abnormalities on chest CT images were evaluated. Patients were divided into four groups based on the thoracic compartment of the predominant radiological abnormality: bronchovascular bundle, lung parenchyma, pleura, and mediastinum groups. The clinical and laboratory characteristics were compared among the four groups. <bold>Results:</bold> Bronchovascular bundle thickening (58.62%), nodular lesions (51.72%), mediastinal/hilar lymphadenopathy (45.26%) and mediastinal soft tissue (31.47%) were the four main thoracic abnormalities. Age, allergy history and respiratory symptoms differed significantly among groups. In terms of organ involvement, the bronchovascular bundle group was associated with lacrimal gland, nasal sinus, and pancreas involvement (p=0.002, 0.006, and 0.049, respectively). Whereas the mediastinum group was associated with retroperitoneum (p<0.001) and extrathoracic lymph node involvement (p=0.010). In terms of laboratory characteristics, the bronchovascular bundle group had higher IgG4 (p=0.005), IgE (p=0.020) and eosinophil count (p=0.001). <bold>Conclusion:</bold> Bronchovascular bundle thickening is the most common abnormality of IgG4-related thoracic disease. The clinical and laboratory characteristics differed among bronchovascular bundle, lung parenchyma, pleura, and mediastinum patterns.