[Exploratory bronchoalveolar lavage].

Bronchoalveolar lavage is a simple technique, complementary to fiberoptic bronchoscopy. The material yielded comprises cells and supernatant, and both components may provide information about the distal lung structures. A few counter-indications should be respected. Normally, the cell differential comprises: 93 +/- 5% alveolar macrophages, 7 +/- 1% lymphocytes and about 1% neutrophils, eosinophils and basophils. Total cellularity and cell differentials are altered in many conditions, according to different patterns, which permits a classification. The increase in numbers may relate to macrophages (smokers, pneumoconiotic disorders...), to lymphocytes (sarcoidosis, hypersensitivity pneumonitis...) and to neutrophils and/or eosinophils (fibrotic disorders, chronic eosinophilic pneumonia, histiocytosis X...). In the last disease, the diagnosis may be established by detecting Langerhans cells. In other conditions, bronchoalveolar lavage mostly provides a trend to diagnosis. Usually well tolerated, bronchoalveolar lavage may usefully be repeated for monitoring patients with chronic interstitial lung disorders. It also gives an insight into the pathogenesis of many pulmonary pathological processes.