Spectrum of fibrotic lung diseases

To the Editor:
The review article by Wijsenbeek and Cottin (Sept. 3 issue)1 provides an excellent overview of the spectrum of fibrotic lung diseases. To this discussion, we would add IgG4-related disease, a distinct primary disease causing interstitial lung disease. IgG4-related disease may affect all parts of the human body (including the lungs), may mimic such conditions as cancer and sarcoidosis, and is an increasingly recognized inflammatory disease characterized by progressive fibrosis. Reported manifestations of IgG4-related lung disease include tumorlike lesions, enlargement of hilar or mediastinal lymph nodes, bronchiectasis, bronchovascular nodules, organizing pneumonia, isolated non-specific interstitial pneumonia,2,3 and interstitial pneumonia with autoimmune features.2-4 The timely diagnosis and treatment of IgG4-related lung disease is important to prevent further progression of fibrosis.