[Epidemiology and Clinical Presentation of Sarcoidosis]

Sarcoidosis is a systemic disease of unknown aetiology. Typical histology shows epithelioid cell granulomas, and typical immunopathology enhanced Th1 type immune responses in the involved organs. The disease occurs worldwide, but more frequently in northern countries than in the south. In Germany, the incidence is estimated to be 10 per 100,000, and the prevalence 44-48 per 100,000. Sarcoidosis usually affects adults under 50 years of age, but can also be seen in children, adolescents and in the elderly. Women are more frequently affected than men. Familial clusters can occur. The clinical presentation of sarcoidosis varies widely and depends on the manifestations in the individual organ. Systemic symptoms include fatigue, night sweats, weight loss, fever, arthralgia and myalgia. Organ-specific symptoms include cough and dyspnoea, with pulmonary involvement, headache and palsy in neurosarcoidosis, arrhythmias and heart failure in cardiac sarcoidosis, and manifold skin lesions with skin involvement. Relapses are rarely seen in acute sarcoidosis, whereas the chronic form tends to relapse more frequently. Löfgren's syndrome, a specific phenotype of acute sarcoidosis, is characterised by bihilar lymphadenopathy, ankle arthritis and erythema nodosum. Chronic sarcoidosis can be asymptomatic, despite radiological changes, which may be extensive. By definition, sarcoidosis has become chronic after 2 years of disease with ongoing signs of activity. The long-term prognosis is generally good, but depends on the different organ manifestations and complications.