[Extrinsic allergic alveolitis. Apropos of a severe case]

A case of atypical extrinsic allergic alveolitis in a 13-year-old is reported. Onset was sudden with gradually increasing dyspnea on exertion over a four-day period. The chest film evidenced a reticulonodular syndrome with decreased respiratory movements. The patient's clinical status worsened over the next 48 hours with the development of respiratory distress. Under oxygen therapy (3 l/min), PO2 was 49 mmHg and SO2 was 82%. Dramatic improvement occurred after initiation of corticosteroid and antimicrobial therapy. Etiologic investigations were negative except for the immunofluorescence test with pigeon droppings which showed three precipitation arcs. A CT scan of the chest disclosed diffuse micronodular densities without thickening of connective tissue trabeculae, suggesting alveolar disease. Mediastinal lymph nodes were not enlarged. Vital capacity was 26% of the theoric value. Corticosteroids were given for one month. On follow-up chest films, the reticulomicronodular syndrome was seen to abate, globally at first, then from the apices to the bases of the lungs. However, a repeat CT scan at the 4th month showed that diffuse lesions were still present although the chest film was normal; 8 months after onset, there was only a bulla in the left lung base, with no evidence of fibrosis. Lung function tests slowly returned to normal, as did CT scan findings.