IgG4-related Respiratory Disease Mimicking Severe Chronic Obstructive Pulmonary Disease with Marked Tracheobronchial Stenosis: A Case Report

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IgG4-related diseases present with various pulmonary lesions, and respiratory dysfunction follows the pattern of pulmonary lesions. Few cases of severe obstructive ventilatory defect have been reported. We experienced a case of IgG4-related respiratory disease with severe obstructive ventilatory defect due to marked thickening of the lower respiratory tract. An 82-year-old woman presented with sputum, cough, and dyspnea on exertion for 4 years. She was considered to have severe chronic obstructive pulmonary disease and was prescribed tiotropium, but her symptoms progressed. Serum IgG4 was elevated, and the chest computed tomography (CT) showed that the bronchial walls thickened with a central predominance and the lobe bronchi were obstructed. Bronchoscopy revealed marked thickening of the trachea and bilateral main bronchi, some of which had pinhole stenosis. Pathological examination of the bronchial wall showed infiltration of IgG4-positive cells, meeting the diagnostic criteria for IgG4-related disease. Treatment with systemic corticosteroid normalized pulmonary function and improved CT findings, and a small maintenance dose of steroids provided long-term stabilization for 11 years. IgG4-related respiratory disease can be a differential disease for obstructive ventilatory defect and have an excellent long-term prognosis. Lower airway thickening on chest CT and high serum IgG4 levels facilitated the diagnosis.