[A misleading form of hypersensitivity pneumonitis]

A 47-year-old woman, without significant past medical history, presented an acute dyspnea with hypoxia, marked pulmonary arterial hypertension (PAH) and signs of right heart failure. Chest x-ray showed a moderate dilatation of the right heart cavities. Pulmonary embolism was suggested. After detailed questioning and complete explorations, a bird hypersensitivity pneumonitis (HP) was demonstrated. This case illustrates a misleading presentation of an acute form of HP consisting of apparently isolated PAH.