Chronic idiopathic bronchiolitis of infancy.

The clinical and morphological features are presented of eight infants who developed a chronic respiratory illness in the first year of life characterised by tachypnoea and inspiratory crackles on auscultation. The median age at the onset of symptoms was 1 month (range 1 day to 7 months). Five of the infants required supplemental oxygen. Chest radiographs showed only non-specific perihilar alveolar shadowing and generalised hyperinflation. Investigations into the cause of the illness in these infants, including studies for infection, cardiac disease, and gastrooesophageal reflux, were negative, and an open lung biopsy sample was subsequently taken from each infant. Histological examination showed mild lymphocytic bronchiolar infiltration only in six of the eight infants. The other two biopsy samples were normal. Seven of the infants were given a trial of steroids by mouth (mean duration of treatment four months) without any apparent benefit. These infants have now been followed up for a median duration of 21 months (range 1-9 years). All have shown continuous improvement, with either the end of oxygen treatment (three patients) or the use of low flow oxygen only at night (two patients). All have normal development and all but one have normal growth. Chest examination has become normal in four subjects. In the remainder the inspiratory crackles have persisted, although they have decreased markedly in all patients. It is proposed that these infants have a previously unreported respiratory entity and that the clinical and lung biopsy sample findings reported here predict a favourable medium term prognosis.