Granulomatous Skin Involvement in a Patient with an Unusual NOD2 Mutation

This case report described a 54-year-old man with a rare heterozygous c.1799A>C(E600A) mutation in the NOD-2 gene, associated with Blau syndrome. Unlike typical cases, this patient exhibited bilateral lower extremity swelling, pain, and decreased hair growth in the affected area, with biopsy revealing non-caseating micro-granulomas. This mutation usually causes uveitis without skin involvement, making this case unique. The patient initially responded well to colchicine, but treatment was discontinued due to elevated transaminases. This report highlighted an unusual genetic form of Blau syndrome with atypical skin involvement and a specific treatment response.