Multicentric Reticulohistiocytosis: A Multicenter Case Series and Review of Literature
Multicentric reticulohistiocytosis (MRH), also known as giant cell histiocytosis, lipoid dermatoarthritis, giant cell reticulohistiocytosis, or reticulohistiocytic granuloma, is a rare inflammatory disease characterized by the development of erosive nodules in the skin, subcutaneous tissues, and synovia, as well as other tissues throughout the body.1 These erosive nodules, composed mainly of multinucleated giant cells and histiocytes, result in papulonodular lesions in the skin and destructive arthritis. Approximately 300 cases have been reported worldwide, mostly in middle-aged white women, although the true prevalence remains unknown likely because of underrecognition and/or underreporting.2 Similarly, pathogenesis of the disease is largely unknown but is believed to be due to stimulation of non–Langerhans cell histiocytes by an as-of-yet unknown precipitating agent. Treatment has largely focused on the use of bisphosphonates, as it may be a disease of osteoclast activation. Even though there are case reports documenting the successful use of bisphosphonates and tumor necrosis factor α (TNF-α) inhibitors, data on long-term outcomes and maintenance regimens are unknown.3
In this article, we describe 6 patients from 2 academic medical centers in the United States who were diagnosed as having MRH. We also describe features of the disease and review the epidemiology, pathophysiology, and management options for MRH.