[Epidemiology of sarcoidosis].

Sarcoidosis is a multisystemic disease in which lung involvement is common. Its incidence and prevalence have been extensively studied, but with contradictory results because of the lack of standard diagnostic criteria, variations in the methods for detecting cases, and the low sensitivity and specificity of diagnostic tests. Prognosis is generally favorable. Many of those affected remain asymptomatic and remission often occurs spontaneously, although between 10% and 30% of the patients have chronic disease and permanent deterioration in lung function. Sarcoidosis is caused by an external agent that triggers a characteristic immune response in genetically susceptible individuals. Environmental, occupational, and genetic factors have all been implicated, but research is still in the early stages. Case-control studies, as well as advances in molecular biology, will help to identify genetic susceptibility factors and to understand the different phenotypes of sarcoidosis.