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Hypersensitivity Pneumonitis — RACP Adult Medicine MCQ

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ModerateRespiratoryHypersensitivity PneumonitisRACP Adult Medicine

A 45-year-old bird breeder presents with recurrent episodes of dyspnoea, fever, and malaise 4–8 hours after cleaning his pigeon loft. HRCT shows ground-glass opacities with mosaic attenuation predominantly in the upper and mid zones. What is the most likely diagnosis?

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Correct answer: C — Hypersensitivity pneumonitis

Recurrent febrile episodes with dyspnoea 4–8 hours after antigen exposure (bird proteins) with ground-glass opacities and mosaic attenuation is classic for hypersensitivity pneumonitis (bird fancier's lung). The temporal relationship to exposure is key. Avoidance of antigen is the cornerstone of management.

Reference: eTG Respiratory – 2024 – Interstitial Lung Disease