Severe progressive erosive arthritis in multicentric reticulohistiocytosis: possible involvement of cytokines in synovial proliferation.

A case of multicentric reticulohistiocytosis complicated by severe progressive erosive arthritis in a 40-year-old man is described. The diagnosis was confirmed by biopsies of the cutaneous nodule and the synovial tissue of the right knee joint. Destructive changes in the multiple joints rapidly progressed and resulted in severe progressive erosive arthritis. Immunohistochemical staining revealed that the histiocytes reacted positively to interleukin 1 beta and platelet derived growth factor B, leading to the speculation that these cytokines may play a role in the synovial proliferation seen in patients with multicentric reticulohistiocytosis.