ABSTRACT
Multicentric reticulohistiocytosis (MRH) is a rare multisystemic granulomatous disease of unknown cause, characterized by severe debilitating polyarthritis and papular to nodular mucocutaneous lesions. This disease usually manifests as a progressive, destructive polyarthritis with mucocutaneous eruptions consisting of erythematous to brownish-colored papules and nodules. MRH is important, not only because of its disfiguring and disabling manifestations and systemic involvements, but also due to its association with internal malignancy. The histological features of skin and synovial lesions are infiltration of multinucleated giant cells, and histiocytes which contain abundant eosinophilic cytoplasm and have a ground glass appearance. Without the accompanying skin nodules, the patients can be misdiagnosed as having rheumatoid arthritis or psoriatic arthritis, and this inaccurate diagnosis will affect treatment. We report a case of MRH which was misdiagnosed as rheumatoid arthritis.