Hypersensitivity pneumonitis revealed by severe asthma: A report of 2 cases

Hypersensitivity pneumonitis (HP) is a complex interstitial lung disease characterized by a heterogeneous clinical presentation that frequently leads to diagnostic delays. While chronic fibrotic forms are well described, clinical presentations mimicking asthma remain a formidable diagnostic pitfall. We report two cases of patients initially followed for refractory severe asthma, in whom thoracic CT imaging and an environmental survey ultimately corrected the diagnosis to HP (specifically "Farmer's Lung" and "Domestic Lung"). These cases illustrate the necessity of investigating for bronchiole-alveolar involvement in any difficult-to-treat asthma: cross-sectional imaging and bronchoalveolar lavage constitute the cornerstones of this re-evaluation.