[Three cases of multicentric reticulohistiocytosis with arthritis].

Multicentric reticulohistiocytosis (MR) is a rare systemic disease of unknown origin that is characterized by a proliferation of histiocytes and multinucleated giant cells. Such changes in the synovium can result in a destructive arthritis, although the mechanism of arthritis in MR is poorly understood. In this paper we present three cases of MR with arthritis. In all three cases, articular symptoms preceded to skin lesions. Articular manifestations of MR were similar to those of rheumatoid arthritis; bilateral symmetric involvement, marginal erosions, and severely destructive arthritis in one case. The diagnosis was confirmed by biopsies of the cutaneous nodules and the synovial tissues of the knee joints. A light microscopic examination of the synovial tissue revealed a proliferation of histiocytes with multinucleated giant forms in the synovial stroma. Further, in one case, a proliferation of synoviocytes with a stratification of lining cells and small vessels were found in the synovium. Prednisolone was administered to all cases, though, the responses were not satisfactory. Further investigation about their clinical courses is necessary.