Treatment: Solitary reticulohistiocytomas are cured with a simple elliptical excision. They rarely recur. Patients with multicentric reticulohistiocytosis require systemic therapy. Screening and constant vigilance for an underlying malignancy is required in all cases. Corticosteroids, methotrexate, hydroxychloroquine, and cyclophosphamide have all been used. Anti–tumor necrosis factor (anti-TNF) agents have been used. The goals are to prevent or suppress the arthropathy and to screen for malignancy.