Erdheim-chester disease

Abstract

Erdheim-Chester disease (ECD) is a non-Langerhans cell histiocytosis and a rare disorder primarily affecting adults. Clinical manifestations vary widely, as does the severity of clinical phenotypes. The disease is defined by infiltration of involved tissues with CD1a (-) histiocytes, inflammation, and fibrosis, although the histopathologic profile of ECD lesions can vary between patients and affected organs. The identification of recurrent somatic alterations in mitogen-activating protein kinase (MAPK) pathway genes in ECD tissue, including the BRAF V600E mutation in ~50% of cases, has led to a reconceptualization of ECD as a myeloid neoplasm. Furthermore, these discoveries have opened the door to new therapeutic strategies holding promise for unprecedented efficacy in the treatment of ECD. Unanswered questions remain about how best to evaluate and implement these new therapies.