Fast Five Quiz: Idiopathic Pulmonary Fibrosis Differential Diagnosis

Guy W. Soo Hoo, MD, MPH; Zab Mosenifar, MD


January 26, 2023

Common lung diseases in the differential diagnosis of IPF include nonspecific interstitial pneumonitis (NSIP), chronic hypersensitivity pneumonia (CHP), and fibrotic sarcoidosis (also referred to as stage 4 sarcoidosis [S4]). Although they have similar clinical presentations and demonstrate substantial overlap on imaging, fibrotic NSIP should be distinguished from IPF, as it has a better prognosis and may respond to steroid therapy.

Symptoms alone are unable to distinguish IPF from NSIP; both cause a progressive cough and shortness of breath. In addition, both generally affect patients over the age of 50 years. However, NSIP is more common in middle-aged women who are nonsmokers, whereas IPF is more common in men aged 55 years or older with a history of smoking. Patients with NSIP may also present with autoimmune features.

High-resolution CT (HRCT) often provides enough information to confirm IPF or NSIP. The classic pattern on HRCT of IPF includes reticulation and honeycombing mainly involving the lung periphery and lower lobes. Honeycomb changes are not common in NSIP. In contrast, HRCT of patients with NSIP most commonly shows ground-glass opacification and increased reticular markings in a predominantly basal and peripheral or diffuse distribution.

When considering other fibrotic-like diseases that share similar presenting signs and symptoms with IPF, bronchitis, pertussis, cystic fibrosis, lung cancer, tuberculosis, pulmonary embolism (PE), pneumonia, and bronchiectasis are not typically included in the differential diagnosis.

Learn more about the differential diagnosis of IPF.


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