Case Report: Blau Syndrome With Thrombocytopenia

We report a case of Blau syndrome in a 22-year-old Chinese female. The patient initially presented with joint swelling and pain at the age of one, subsequently developing a generalized rash and uveitis. Initially diagnosed with juvenile idiopathic arthritis, she was treated based on this diagnosis. However, genetic testing conducted in 2020 revealed a heterozygous mutation, C. 1538(exon 4)T > C, in the NOD2 gene (NM_022162), resulting in the substitution of methionine with threonine at position 513 of the encoded protein (p. M513T). This finding led to the re-diagnosis of Blau syndrome. The patient exhibited intermittent hemorrhagic lesions on the skin of both lower extremities on three occasions—in 2011, 2022, and 2024—and was subsequently diagnosed with severe thrombocytopenia upon hospitalization. Analyzing and summarizing this case can provide valuable insights into the clinical characteristics of Blau syndrome, thereby contributing a deeper understanding of this rare condition.