Erdheim-Chester disease (ECD) is a rare condition affecting many parts of the body. Although diagnosed in some children, it most commonly affects adults. ECD causes the overproduction of histiocytes, which then accumulate in tissues and organs. Parts of the body that may be involved include the long bones, retroperitoneum, skin, eyes and eyelids, lungs, brain, heart, kidneys, and pituitary gland. However, various other tissues or organs can be affected.
Etiology
The underlying cause of ECD is unknown but thought to be associated with a TH1 immune response. Some people with ECD test positive for an acquired genetic change in the BRAF gene (in about half of patients) or one of several other genes. These genetic changes may allow histiocytes to reproduce uncontrollably.
Signs and Symptoms
The signs and symptoms of ECD vary from person to person depending upon the specific locations and extent of involvement. The long bones of the legs are commonly affected, leading to bone pain. When tissues around the eyes are affected, a person may have soft, fatty bumps on the eyelids or protrusion of the eyeballs. Lung involvement may cause pulmonary fibrosis, which can lead to severe complications. People with pituitary gland involvement may develop diabetes insipidus, and brain involvement may lead to various neurologic symptoms. Non-specific symptoms that may develop include weight loss, weakness, fever, muscle and joint aches, and malaise.
Diagnosis
A diagnosis of ECD is based on symptoms, biopsies of involved tissue examined under a microscope, and specialized tests that may include blood tests and imaging studies such as X-rays, CT scans, MRIs, and bone scans. Diagnostic confirmation is made upon detection of CD68(+), CD1a(−) non Langerhans histiocytes with foamy or eosinophilic cytoplasm lacking Birbeck granules.
Management Strategies and Treatment
Currently, there are no approved treatments targeting the underlying cause of disease. However, interferon-alpha is the first line of treatment for ECD, providing sustainable stabilization of the disease and improved survival. Other treatment alternatives include cladribine (2CDA), corticosteroids, chemotherapy, and vemurafenib.
Clinical Trials and Studies
For a full list of clinical trials relating to, click here.
Resources
Erdheim-Chester Disease Global Alliance
References
Mazor R et al. Erdheim-Chester Disease: a comprehensive review of the literature. In: Orphanet Journal of Rare Diseases. Available at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3849848/
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