Clinicopathologic characteristics of pulmonary acinar sarcoidosis

Acute alveolar sarcoidosis presenting with hypoxaemic respiratory failure

Alveolar sarcoidosis is a less commonly seen pulmonary manifestation of the disease. An acute presentation of this radiological pattern with hypoxaemic respiratory failure has been documented only once, four decades ago. A 30-year-old man presented with acute onset of progressive and persistent dyspnoea over 20 days ago with hypoxaemic respiratory failure. Imaging demonstrated mediastinal lymphadenopathy and coalescent parenchymal alveolar opacities having ill-defined margins along with air bronchograms in the mid and lower zones bilaterally, suggestive of alveolar sarcoidosis. A restrictive pattern with a diffusion defect was seen on pulmonary function testing. Bronchoscopic evaluation revealed non-caseating granulomas on histopathology confirming pulmonary sarcoidosis. This was further supported by an elevated serum ACE level and negative Mantoux test. Oral prednisolone elicited a rapid clinical and radiological response. Alveolar sarcoidosis can rarely present acutely with hypoxaemic respiratory failure, which can respond remarkably and expeditiously to appropriate therapy.

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.