Pulmonary sarcoidosis with an alveolar radiographic pattern.

Thirty-three cases of sarcoidosis (4.4% of 746 patients) showed an alveolar radiological pattern. A study of pulmonary function was carried out in 25 patients and compared with that of 46 patients with the interstitial radiological type of sarcoidosis. Twenty-two cases have been followed up from one to six years after the initial examination. The radiographic lesions were most often bilateral and included nodules greater than 15 mm with ill-defined margins or diffuse, infiltrative, non-retractile opacities with fluffy margins. Bilateral mediastinal lymph nodes were present in 27 patients. In 20 patients an associated reticulation was found on radiography. In four patients an open lung biopsy was done. The granulomatous nodules were identical to those found in other forms of sarcoidosis, although they were more confluent in the affected areas. Clinical and functional findings did not differ from those in the more common forms of sarcoidosis. Alveolar sarcoidosis has a sudden course. The alveolar radiological patterns always disappeared, with or without steroid treatment, while reticular patterns persisted in four patients. Rapid radiological changes were observed. Some functional abnormalities persisted in cases that were followed. It is concluded that alveolar sarcoidosis is a distinct acute form of sarcoidosis.