[Data of broncho-alveolar lavage and pulmonary histiocytosis X].

: The data obtained from broncho-alveolar lavage in 12 cases of pulmonary histiocytosis X explored between 1978 and 1986 are reported. The usefulness of this simple and reliable examination to the diagnosis and follow-up is emphasized. The diagnosis, suggested by radiography of the chest, may be suspected on cytological findings of hypercellularity, macrophage alveolitis and eosinophilia. The occurrence of neutrophilic hypergranulocytosis indicates an unfavourable course towards fibrosis. An increase of cells marked with monoclonal OKT6 antibodies (70% of the cases in this series) contributes to the diagnosis of histiocytosis X and is a good indicator of granuloma activity during the follow-up period. Electron microscopy of the alveolar fluid often confirms the diagnosis by showing the specific organelle: the X granule (60% of the cases in this series), thus avoiding exploratory thoracotomy in many patients.