NOD2 and dermatitis: Different from “classic” sarcoidosis (usually without hilar lymphadenopathy and interstitial fibrosis) and typical of preschool age are the granulomatous auto-inflammatory diseases including the familial form known as Blau syndrome (BS, OMIM 186580) and the sporadic form known as early-onset sarcoidosis (EOS, OMIM 609464); both are caused by mutations in the NOD2/CARD15 gene and characterized by the clinical triad of granulomatous recurrent panuveitis, dermatitis, and symmetric arthritis with large, boggy synovial effusions and tenosynovial cysts particularly affecting the wrists and ankles.