Nijmegen breakage syndrome and chronic polyarthritis.

We report on pediatric patient with Nijmegen breakage syndrome (NBS), a rare DNA repair disorder characterized by microcephaly, immunodeficiency and predisposition to malignant lymphomas, who developed juvenile idiopathic arthritis (JIA)-like polyarthritis. In patients with primary immunodeficiencies (PID), septic arthritis due to pyogenic bacteria or mycoplasmal arthritis are the most common osteoarticular manifestations. In certain PID, chronic, non-infectious arthritis resembling rheumatoid arthritis may occur. In our patient microbiologic cultures of synovial fluid including Mycoplasma spp. were negative. At first, because of suspected mycoplasmal arthritis we used macrolides and doxycycline combined with hydroxychloroquine but without therapeutic response. However, the use of rituximab led to remission of her polyarthritis lasting for 9 months. Autoimmune features were rarely reported in NBS. An occurrence of JIA-like, chronic polyarthritis in NBS, a DNA repair disorder characterized by decreased tolerance of immunosuppressive drugs such as methotrexate and a high natural risk for lymphomas, makes therapeutic approach even more complex.