In 2016, the World Health Organization (WHO) defined ECD as a slow-growing blood cancer that may originate in the bone marrow or precursor cells.
[6][7] Orbital involvement is also common in ECD, with approximately 25% of patients developing bilateral and symmetrical exophthalmos as the disease progresses.
[6] Diagnosis can often be challenging due to several factors, including unclear biopsy findings, the rarity of ECD cases, and the need to distinguish it from LCH.
For these reasons, ECD is often diagnosed based on a combination of histology, clinical symptoms, imaging features, and the presence of mutations in the MAPK/ERK and PI3K/AKT pathways.
It would appear that approximately half these patients harbor point mutations of the BRAF gene at codon 600 substituting the amino acid glutamine for valine.
The presence of symmetrical cerebellar and pontine signal changes on T2-weighted images seem to be typical of ECD, however, multiple sclerosis and metabolic diseases must also be considered in the differential diagnosis.
[9] Unlike LCH, ECD does not stain positive for S-100 proteins or Group 1 CD1a glycoproteins, and electron microscopy of cell cytoplasm does not disclose Birbeck granules.
Psychological support is important, as effective physical treatment often leads to a chronic condition, which may involve various challenges, deficits, and secondary complications.
Recent research findings on the disease's genomic structure, especially mutations in the mitogen-activated protein kinase/extracellular signal-regulated kinase pathway, have enabled the use of targeted therapies for most patients.
[23] The Erdheim–Chester Disease Global Alliance is a support and advocacy group with the goal of raising awareness of and promoting research into ECD.
[24][25] ECD families and patients are also supported by the Histiocytosis Association, Inc.[25][26] In the TV show House, season 2 episode 17, "All In", the initial and final diagnosis of a 6-year-old boy who presents with bloody diarrhea and ataxia is Erdheim–Chester disease.