Children of both sexes develop sarcoidosis less commonly than adults. The clinical manifestations in older children are similar to those in adults. However, in children younger than 5 years the characteristic presentation includes mild constitutional symptoms; painless, boggy, and effusive large-joint polyarthritis and tenosynovitis; skin lesions; uveitis; and lymphadenopathy and splenomegaly without typical lung disease.This presentation must be differentiated from the rare autosomal dominant familial granulomatous disorder Blau syndrome, which is caused by a genetic mutation of the NOD2/CARD15 protein. Children with sarcoidosis usually have a spontaneous resolution of disease, but some experience residual complications. Corticosteroids with or without methotrexate are the treatment of choice for children with severely symptomatic or progressive disease.