Pneumopathies d'hypersensibilité

Hypersensitivity pneumonitis is due to chronic inhalation of antigenic substances, organic most of the time. A lymphocytic and granulomatous infiltration is observed in pulmonary interstitium. Diagnosis is based on associated clinical and paraclinical signs among which exposure, lymphocytic alveolitis in BAL, and HRCT scan images associating bilateral ground glass opacities and ill-defined micronodules, are essential. Early removal of exposure prevents in most cases the occurrence of chronic respiratory failure by fibrosis or emphysema. Sometimes, especially in farmers, a decreased exposure allows to continue occupational activities without excessive risks. Corticosteroids can be used in severe forms during few weeks, but they do not prevent further (late) recurrence.