Idiopathic pulmonary fibrosis (IPF) is a nonneoplastic pulmonary disease that is characterized by the formation of scar tissue within the lungs in the absence of any known cause.
IPF is a rare disease that affects approximately 5 million people worldwide. The prevalence is estimated to be slightly higher in men (1/5000) than in women (1/7700).
The mean age at presentation is 66 years. IPF initially manifests with symptoms of exercise-induced breathlessness and dry coughing. Auscultation of the lungs reveals early inspiratory crackles, predominantly located in the lower posterior lung zones. Clubbing is found in approximately 50% of IPF patients. Cor pulmonale develops in association with end-stage disease and classic signs of right heart failure may be present.
The etiology is not yet completely understood. Environmental factors may be associated with IPF (cigarette smoking, exposure to silica and livestock).
IPF is recognized on high-resolution computed tomography by peripheral, subpleural lower lobe reticular opacities in association with subpleural honeycomb changes. IPF is associated with a pathological lesion known as usual interstitial pneumonia (UIP). The UIP pattern consists of normal lung alternating with patches of dense fibrosis, taking the form of collagen sheets. The diagnosis of IPF requires correlation of the clinical setting with radiographic images and a lung biopsy. In the absence of lung biopsy, the diagnosis of IPF can be made by defined clinical criteria that have been published in guidelines endorsed by several professional societies.
Differential diagnosis includes other idiopathic interstitial pneumonias, connective tissue diseases (systemic sclerosis, polymyositis, rheumatoid arthritis), forme fruste of autoimmune disorders, chronic hypersensitivity pneumonitis (see these terms) and other environmental (sometimes occupational) exposures.
Medical therapy is ineffective in the treatment of IPF. New molecular therapeutic targets have been identified and several clinical trials are investigating the efficacy of novel medications. Meanwhile, pulmonary transplantation remains a viable option for patients with IPF. However, IPF is typically progressive and leads to significant disability.
The median survival is 2 to 5 years from the time of diagnosis.
Last update: March 2008
- Dr Eric MELTZER
- Pr Paul NOBLE