The cause of the disease is unknown. Tissue samples from involved organs show granulomas, which are clusters of macrophages, lymphocytes, and cells called multinucleated giant cells. Possible causes include a hypersensitivity response, a genetic predisposition, infection, or chemicals. The incidence varies widely according to race and sex. Incidence is highest among North Americans of African heritage and Northern European Caucasians. Women of African heritage are affected more than men of African heritage. The onset of the disease usually occurs in people between 30 and 50 years old. Sarcoidosis is very rare in young children.
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