Erdheim–Chester disease

PURPOSE OF REVIEW: Erdheim-Chester disease (ECD) is a rare, non-Langerhans form of histiocytosis first described in 1930 with a wide range of manifestations. The number of new cases has dramatically increased over the past 10 years because of the better recognition of this condition. The natural evolution is variable, but the spontaneous prognosis is severe. In this review, we describe the relevant clinical, radiological, prognostic, and therapeutic features of this orphan disease. RECENT FINDINGS: Compelling evidence demonstrates the efficacy of treatment by interferon alpha (IFNα) which has been reported to be a major independent predictor of survival among ECD patients. Alternative treatments remain to be defined. Recent studies have highlighted the central nervous system involvement as an independent predictor of death. Pathophysiology is better understood with a complex network of cytokines and chemokines and a systemic immune Th-1-oriented perturbation. SUMMARY: ECD, although a rare and orphan disease, has been overlooked and numerous new cases are currently diagnosed because of general better knowledge of this histiocytosis. First-line treatment is IFNα. We have recently described a unique cytokine signature that may provide further clues to understand the pathogenesis of ECD, as well as provide new tools for diagnosis and targeted therapy.