Malignant histiocytosis presenting as interstitial pulmonary disease.

Three children presented with progressive respiratory symptoms and radiographic evidence of diffuse interstitial infiltrates. All three had a pulmonary pathologic diagnosis of malignant histiocytosis. The pulmonary manifestations of this disease appear to have been responsive to combined chemotherapy. Malignant histiocytosis needs to be considered in the differential diagnosis of interstitial pulmonary disease.