The early symptoms of IPF, dyspnoea upon exertion and a dry cough, are commonly mistaken for aging, cardiac disease, emphysema, bronchitis, asthma or COPD.1 Such misdiagnosis, or ignoring the early symptoms entirely, may explain why IPF is rarely diagnosed immediately. Often a correct diagnosis may take several months or even years.2
In order to conclusively diagnose idiopathic pulmonary fibrosis (IPF), a number of other lung diseases must be excluded. Other idiopathic interstitial pneumonias as well as other forms of diffuse parenchymal lung disease, such as Sarcoidosis or infections, must be ruled out (see figure below).3 Considerable ground glass opacity and/or nodular patterns found using HRCT may be indicative of idiopathic interstitial pneumonias other than IPF.2
It is of crucial importance to distinguish IPF from the other forms of interstitial pneumonia due to differences in prognosis4 and treatment responses.5
Lung diseases associated with environmental factors, such as exposure to asbestos, side effects of medications or a systemic disease that may be affecting the lungs indirectly, must also be excluded.
These differential diagnostic considerations include systemic sclerosis, polymyositis, rheumatoid arthritis and other connective tissue diseases, some atypical autoimmune disorders, and several congenital disorders.2