[Why, when and how to treat sarcoidosis?].

The natural history of sarcoidosis is favourable in 90% of cases; in 10% deterioration occurs with the appearance of respiratory failure, aspergillous or tuberculous infections which cause death in 5% of patients. Thus the problem for the clinician is the early detection and treatment of those patients whose outcome will be unfavourable. Certain clinical pointers exist measuring the activity and the dissemination of the sarcoidosis as well as its consequences. Among these are radiology, biological tests (such as the serum angiotensin converting enzyme of differential cell counts on bronchoalveolar lavage), scintigraphy and respiratory function; despite the above it is more difficult to determine the prognosis early as in practice this is decided by repetitive screening tests. Steroid therapy seems more effective than other treatments. But drugs cannot be held responsible for those cures which occur apparently unrelated to the treatment received; the occurrence of relapses after interruptions of treatment demand prolonged treatment if an unfavourable outcome is suspected.