Idiopathic pulmonary fibrosis vs Hypersensitivity pneumonitis
How to tell Idiopathic pulmonary fibrosis and Hypersensitivity pneumonitis apart when a board question makes them look alike.
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Clear antigen exposure history with BAL lymphocytosis favors hypersensitivity pneumonitis over idiopathic pulmonary fibrosis.
Side by side
Progressive exertional dyspnea with bibasilar crackles and usual interstitial pneumonia pattern on HRCT indicates idiopathic pulmonary fibrosis.
Dyspnea and cough linked to bird or mold exposure with centrilobular nodules and ground-glass opacities suggests hypersensitivity pneumonitis.
Repeated epithelial injury leads to fibroblast activation and irreversible interstitial fibrosis with honeycombing.
Inhaled organic antigens trigger immune-mediated alveolar inflammation that may improve with antigen removal and corticosteroids.
HRCT shows basal and subpleural reticulation with honeycombing and traction bronchiectasis, PFT shows restrictive defect with reduced DLCO, and BAL is not lymphocyte-predominant.
HP often shows exposure history, HRCT with upper or mid-lung ground-glass and centrilobular nodules, BAL lymphocytosis above 20%, and precipitating IgG antibodies to culprit antigen.
The trap
Both diseases can show restrictive physiology, so clinicians overcall IPF in exposed patients. The resolving clue is exposure-linked symptom fluctuation plus inflammatory imaging pattern rather than basal honeycombing.
The repair move
Next best step: remove ongoing antigen exposure immediately and start oral prednisone 0.5 mg/kg/day for symptomatic subacute hypersensitivity pneumonitis, then taper over weeks based on clinical and pulmonary function response. If HRCT shows usual interstitial pneumonia without exposure signal, initiate antifibrotic therapy such as nintedanib or pirfenidone and refer for lung transplant evaluation when advanced.
Try a free question
CoreA 58-year-old man has progressive dyspnea for 2 years. BP 130/80 mm Hg, HR 88/min, temp 36.8 C. HRCT shows basilar subpleural honeycombing with traction bronchiectasis and no relevant exposure history. What is the next best step in management?
Show answer and explanation
Answer: A. Start nintedanib therapy. Classic IPF with usual interstitial pneumonia pattern is treated with antifibrotic therapy to slow progression.
Why the other choices are tempting
- B. No evidence suggests bacterial pneumonia as the main process.
- C. Prolonged high-dose steroids are not standard first-line for stable IPF.
- D. Observation alone misses disease-modifying treatment opportunity.
- E. No findings indicate active tuberculosis.
Flashcards
Tap a card to flip it.
Which HRCT pattern is most characteristic of idiopathic pulmonary fibrosis?
Basal subpleural honeycombing with traction bronchiectasis is characteristic of usual interstitial pneumonia in IPF.
What history clue strongly favors hypersensitivity pneumonitis over IPF?
Respiratory symptoms linked to bird, mold, or farm antigen exposure that improve away from exposure favors HP.
Quick answers
What is the fastest way to tell Idiopathic pulmonary fibrosis from Hypersensitivity pneumonitis?
Clear antigen exposure history with BAL lymphocytosis favors hypersensitivity pneumonitis over idiopathic pulmonary fibrosis.
What is the key clue for Idiopathic pulmonary fibrosis?
Progressive exertional dyspnea with bibasilar crackles and usual interstitial pneumonia pattern on HRCT indicates idiopathic pulmonary fibrosis.
What is the key clue for Hypersensitivity pneumonitis?
Dyspnea and cough linked to bird or mold exposure with centrilobular nodules and ground-glass opacities suggests hypersensitivity pneumonitis.
What is the common trap with Idiopathic pulmonary fibrosis vs Hypersensitivity pneumonitis?
Both diseases can show restrictive physiology, so clinicians overcall IPF in exposed patients. The resolving clue is exposure-linked symptom fluctuation plus inflammatory imaging pattern rather than basal honeycombing.