[Interstitial pneumopathies caused by busulfan. Histologic, developmental and bronchoalveolar lavage analysis of 3 cases].

Busulfan-induced diffuse interstitial pneumonia is a rare but serious disease attributed to a direct toxic effect of busulfan (an alkylating antimitotic drug) on alveolar cells. We report three new cases explored by repeated bronchoalveolar lavages and lung biopsies. All patients had circulating immune complexes, abnormalities at capillaroscopy and above all lymphocytic or mixed alveolitis at bronchoalveolar lavage. The clinical outcome was favourable with regression of the alveolar lesions in the patient with pure lymphocytic alveolitis. It was unfavourable in patients showing severe alveolitis with polymorphonuclear cells. Histology revealed constant abnormalities of type I pneumocytes and rarefaction of type II pneumocytes, together with interstitial oedema and pulmonary fibrosis in which tissue mast cells could not be identified. The immunological disturbances observed in busulfan lung might enhance an initial toxic reaction and account for the often unfavourable outcome, even after withdrawal of busulfan.