The challenge offered by patients presenting roentgenographic features (Fig. 1) of diffuse bilateral fibronodular disease often has been a particularly frustrating experience for many clinicians. The symptom complex usually encountered in this group of patients is the syndrome of alveolar-capillary block.2 That a wide variety of etiologic factors can produce this clinical defect and pulmonary pattern has been well documented.1,2,5,6 It is apparent that an accurate diagnosis of these lesions is essential for rational therapy, careful prognosis, and recovery of the patient. This is often possible only by histologic examination of the pulmonary lesion.
This report is based on the results of pulmonary biopsy in thirty-four patients who presented a picture of alveolar-capillary block syndrome and thoracic roentgenograms demonstrating bilateral, diffuse, fibronodular disease. In none of the patients had the diagnosis been confirmed by any means except pulmonary biopsy. Those patients in whom diagnoses were made by bacteriologic,