Erdheim-Chester Disease

Erdheim-Chester disease (ECD) is a rare disorder and blood cancer characterized by an abnormal increase in cells called histiocytes within the tissues and organs in the body. Histiocytes are normally found in areas like the skin, liver, bone marrow, or the bloodstream; and usually respond to injuries and infections. With ECD, the increased number of histiocytes migrate to different parts of the body, such as the eyes, long bones, brain, or pituitary gland and cause damage—usually in the form of tumors and chronic, uncontrolled inflammation.  

ECD is a type of non-Langerhans cell histiocytosis. Histiocyte disorders can be divided into Langerhans cell histiocytosis (LCH) and non-Langerhans cell histiocytosis. LCH is derived from the Langerhans cells, which are a part of the cutaneous immune system. Conversely, non-Langerhans cell histiocytosis originates from monocytes and macrophages, which are a part of the innate immune system that removes harmful or foreign invaders. 

Treatment will depend on various factors, but first-line treatment generally consists of immunotherapy, like interferon. Other treatment options can include BRAF inhibitors, like vemurafenib, in those who test positive for a mutation in the BRAF gene. Other targeted therapies can include MEK inhibitors (e.g., cobimetinib), glucocorticoids, and cytotoxic chemotherapy agents like cladribine. Surgery is rarely considered due to the typical extensive dissemination of the condition.  

There is no cure for ECD; however, an individual can live many years with appropriate treatment. Some studies suggest that when treatment ceases, the condition will quickly progress; therefore, treatment can be lifelong.