Monoarthritis in children as first manifestation of a X-linked agammaglobulinemia (M. Bruton).

Introduction: There are different causes for knee joint effusions in children. Rheumatoid diseases and hematogenous septic arthritis are the most important differential diagnoses. It is less known that immunodeficiency syndroms may cause serous monarthritis. Results: A case of a five years old boy with monarthritis of the knee is presented. Blood assay and specific immunologic analysis revealed a so far unknown X-linked agammaglobulinemia (M. Bruton). Conclusions: In case of a monarthritis in children the orthopaedic surgeon or the pediatrician is primarily involved. For differential diagnosis X-linked agammaglobulinemia should be considered as reason for monarthritis, especially, if there are other clues to that disease in the medical history. In the case of agammaglobulinemia effusion and swelling will decrease soon after treatment with intravenous gammaglobulin.