Acute interstitial pneumonia: report of a series.

Four cases of acute interstitial pneumonia (AIP) are described with special emphasis on clinical background, lung imaging and bronchoalveolar lavage findings. A retrospective chart review of four patients with histologically-proven AIP, diagnosed between 1998 and 2000, was carried out. Clinical data, bronchoalveolar lavage (BAL) findings, high-resolution computed tomography (HRCT) and histological features were analysed. Three patients died and only one is in follow-up. HRCT showed areas of ground glass attenuation and alveolar consolidation in all patients. Histology, documented by open lung biopsy or autopsy specimens, was consistent with the organising form of diffuse alveolar damage pattern. BAL findings were characteristic, with a huge neutrophilia associated with scattered atypical type II pneumocytes collected in clusters with extracellular amorphous material (fragments of hyaline membranes) observed in two out of three cases. In this paper, four cases of acute interstitial pneumonia are reported in detail. The poor prognosis associated with this entity has been confirmed and the possible diagnostic role of the bronchoalveolar lavage is emphasised.