[An unusual cause of pulmonary cysts].
INTRODUCTION: Multiple pathologies may be associated with cystic appearances in the lungs. Lymphangioleiomyomatosis, Langerhans cell histiocytosis and lymphocytic interstitial pneumonia are the principal causes of thin walled pulmonary cysts. CASE REPORT: We report the case of a non-smoking woman of 71 years, a retired farmer, who was admitted on account of cough, increasing dyspnoea, fever and loss of weight that developed following exposure to hay. The thoracic CT scan revealed diffuse ground glass opacities and centrilobular nodules. Multiple thin walled cystic shadows were distributed homogeneously throughout both lung fields. Broncho-alveolar lavage revealed a marked lymphocytosis (63%) and precipitins for Microsporum Faeni were strongly positive (6 arcs). The respiratory symptoms resolved spontaneously during the stay in hospital, allowing the patient to be discharged after 3 weeks with the advice to avoid all contact with hay. One month later she remained symptom free, the repeat CT scan showed a diminution ofthe ground glass opacities and the nodules but persistence of the pulmonary cysts. CONCLUSION: The diagnosis of hypersensitivity pneumonitis should be considered in the presence of a diffuse pulmonary infiltrate with multiple thin walled cysts in a patient with a suggestive history and clinical picture.