Interstitial lung disease

Interstitial lung disease (ILD) refers to a broad and heterogeneous group of rare pulmonary disorders characterized by inflammation and/or fibrosis of the lung interstitium — the tissue and space surrounding the air sacs (alveoli) of the lungs. These conditions impair the normal gas exchange function of the lungs, leading to progressive respiratory insufficiency. ILD encompasses numerous specific entities, including idiopathic pulmonary fibrosis, nonspecific interstitial pneumonia, cryptogenic organizing pneumonia, lymphoid interstitial pneumonia, desquamative interstitial pneumonia, and others. The disease primarily affects the respiratory system but can also be associated with systemic autoimmune or connective tissue disorders, environmental or occupational exposures, drug toxicity, or may arise without an identifiable cause (idiopathic forms). Key symptoms of ILD include progressive exertional dyspnea (shortness of breath with activity), persistent dry cough, fatigue, and reduced exercise tolerance. As the disease advances, patients may develop digital clubbing, cyanosis, and signs of right-sided heart failure (cor pulmonale). High-resolution computed tomography (HRCT) of the chest is a critical diagnostic tool, often revealing characteristic patterns such as ground-glass opacities, reticular markings, honeycombing, or traction bronchiectasis depending on the specific subtype. Pulmonary function testing typically shows a restrictive ventilatory defect with reduced diffusing capacity for carbon monoxide (DLCO). The treatment landscape for ILD varies significantly depending on the underlying subtype and etiology. For idiopathic pulmonary fibrosis, antifibrotic agents such as pirfenidone and nintedanib have been shown to slow disease progression. Inflammatory or autoimmune-related ILDs may respond to corticosteroids and immunosuppressive therapies such as mycophenolate mofetil or azathioprine. Supportive care including supplemental oxygen therapy and pulmonary rehabilitation plays an important role in managing symptoms and maintaining quality of life. Lung transplantation remains an option for eligible patients with advanced, progressive disease refractory to medical therapy. Prognosis is highly variable, ranging from self-limited conditions to relentlessly progressive fibrosis.

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

Common questions about Interstitial lung disease