Idiopathic pulmonary fibrosis vs Hypersensitivity pneumonitis
How to tell Idiopathic pulmonary fibrosis and Hypersensitivity pneumonitis apart when a board question makes them look alike.
IPF is idiopathic basilar subpleural honeycombing; hypersensitivity pneumonitis is exposure-linked immune ILD with bronchiolocentric small-airway clues.
Side by side
Older adult with progressive dry cough, exertional dyspnea, restrictive physiology, bibasilar crackles, and basilar subpleural honeycombing without an exposure trigger.
Immune lung disease after repeated inhaled antigen exposure, with symptoms tied to birds, mold, farming, hot tubs, or occupational antigens and CT small-airway clues.
Usual interstitial pneumonia pattern reflects progressive fibroblast activity and architectural distortion without a known cause.
Repeated antigen inhalation triggers immune-mediated bronchiolocentric inflammation that can become fibrotic if exposure continues.
Lower-lobe subpleural reticulation and honeycombing, traction bronchiectasis, and no exposure story points IPF.
Exposure-linked flares, centrilobular nodules, mosaic attenuation, air trapping, and improvement with antigen avoidance points hypersensitivity pneumonitis.
The trap
Fibrotic hypersensitivity pneumonitis can mimic IPF, so exposure history is not optional.
Watch it explained
The repair move
For fibrotic ILD, ask whether the CT pattern is classic UIP and whether a repeatable antigen exposure exists.
Try a free question
CoreAn older adult has progressive exertional dyspnea, dry cough, bibasilar inspiratory crackles, restrictive PFTs, and high-resolution CT with lower-lobe subpleural honeycombing. No exposure trigger is found. Which diagnosis is most likely?
Show answer and explanation
Answer: A. Idiopathic pulmonary fibrosis. Idiopathic pulmonary fibrosis classically shows usual interstitial pneumonia pattern with basilar, subpleural reticulation and honeycombing in an older adult.
Why the other choices are tempting
- B. Hypersensitivity pneumonitis needs an antigen exposure pattern and often has centrilobular nodules or mosaic attenuation.
- C. Sarcoidosis usually causes noncaseating granulomas and bilateral hilar adenopathy.
- D. Berylliosis mimics sarcoidosis after beryllium exposure.
- E. Asthma is obstructive and reversible rather than restrictive fibrotic disease.
Flashcards
Tap a card to flip it.
What is the fastest separator for Idiopathic pulmonary fibrosis vs Hypersensitivity pneumonitis?
IPF is idiopathic basilar subpleural honeycombing; hypersensitivity pneumonitis is exposure-linked immune ILD with bronchiolocentric small-airway clues.
What clue should make you choose Idiopathic pulmonary fibrosis?
Older adult with progressive dry cough, exertional dyspnea, restrictive physiology, bibasilar crackles, and basilar subpleural honeycombing without an exposure trigger.
Quick answers
What is the fastest way to tell Idiopathic pulmonary fibrosis from Hypersensitivity pneumonitis?
IPF is idiopathic basilar subpleural honeycombing; hypersensitivity pneumonitis is exposure-linked immune ILD with bronchiolocentric small-airway clues.
What is the key clue for Idiopathic pulmonary fibrosis?
Older adult with progressive dry cough, exertional dyspnea, restrictive physiology, bibasilar crackles, and basilar subpleural honeycombing without an exposure trigger.
What is the key clue for Hypersensitivity pneumonitis?
Immune lung disease after repeated inhaled antigen exposure, with symptoms tied to birds, mold, farming, hot tubs, or occupational antigens and CT small-airway clues.
What is the common trap with Idiopathic pulmonary fibrosis vs Hypersensitivity pneumonitis?
Fibrotic hypersensitivity pneumonitis can mimic IPF, so exposure history is not optional.