Fast Five Quiz: Idiopathic Pulmonary Fibrosis Differential Diagnosis

Guy W. Soo Hoo, MD, MPH


November 20, 2019

Stage 4 sarcoidosis can clinically mimic IPF. Sarcoidosis is a multisystem granulomatous disease that primarily affects the lungs. Similar to IPF, the etiology of sarcoidosis is unknown. Although patients with stage 1, 2, or 3 pulmonary sarcoidosis often experience periods of remission and favorable long-term outcomes, approximately 20% develop pulmonary fibrosis and progress to end-stage disease (S4).

Differences in histology between S4 and IPF can help in the differential diagnosis. The typical histologic honeycombing pattern and fibroblast foci associated with IPF/UIP are not typically seen in sarcoidosis. In addition, the nonproductive cough associated with IPF/UIP is typically not present in patients with S4.

Imaging modalities to follow patients and guide treatment are also different for S4 and IPF. Positron emission tomography (PET) scan is more helpful than HRCT scan in these patients, and is used to monitor inflammation and guide treatment. The treatment plan for S4 includes anti-inflammatory and immunosuppressive agents including azathioprine, corticosteroids, leflunomide, and methotrexate.

For more on stage 4 sarcoidosis, read here.


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