Obliterative bronchiolitis with atypical features: CT scan and necropsy findings

We describe the natural history of cryptogenic bronchiolitis obliterans in a patient followed for 24 yrs with serial pulmonary function tests and radiology. Severe, progressive airway obstruction developed, with overinflation but preservation of KCO. There was progressive hypoxaemia, which worsened on exertion; hypercapnoea was modest until late in the illness. Neither bronchodilators nor steroids were effective. The chest radiograph remained normal; CT showed irregular areas of low attenuation peripherally throughout the lungs, with Hounsfield numbers typical of emphysema, but no bullae. Postmortem studies included histology and quantitative studies of a corrosion cast of one lung. They showed marked airway narrowing at all levels, with pruning of peripheral branches, mucus plugging, and some emphysema. The case illustrates that cryptogenic bronchiolitis obliterans may be chronic and difficult to distinguish clinically or by investigation from other forms of chronic obstructive airways disease, particularly emphysema.