Children with pulmonary Langerhans'-cell histiocytosis present in a variety of ways. They can be asymptomatic or present common symptoms such as nonproductive cough and dyspnea. HRCT of the chest is a useful and sensitive tool for the diagnosis. Indeed, the combination of diffuse, irregularly shaped cystic spaces with small peribronchiolar nodular opacities, predominantly in the middle and upper lobe, is highly suggestive of pulmonary Langerhans'-cell histiocytosis [63] . Other abnormalities include ground-glass attenuation. The presence of increased numbers of Langerhans' cells in BAL fluid (identified by staining with antibodies against CD1a) with a proportion greater than 5 percent is also strongly suggestive of pulmonary Langerhans'-cell histiocytosis.