Interstitial pneumonia associated with linear immunoglobulin A/immunoglobulin G bullous dermatosis

A 76-year-old man with interstitial lung disease was admitted to our institution after developing persistent dyspnea upon effort. He also had a relapse of bullous eruptions on the skin of the trunk and extremities, previously diagnosed as vesicular pemphigoid. Direct immunofluorescence of a skin biopsy specimen using fluorescence microscopy showed the linear deposition of immunglobulin A (IgA), IgG and C3 along the basement membrane. These findings indicated a definitive diagnosis of linear IgA/IgG bullous dermatosis. Chest computed tomography, bronchoalveolar lavage and transbronchial lung biopsy findings suggested nonspecific interstitial pneumonia. Direct immunofluorescence of the lung biopsy specimens using fluorescence microscopy also showed a deposition of IgA, IgG and C3 along the epithelial cell membranes and basement membranes of the bronchioles and alveoli. Lung disorders associated with linear IgA/IgG bullous dermatosis are extremely rare and, to our knowledge, this is the first report of such a case of interstitial pneumonia.