Question: What is (are) Erdheim-Chester disease ?
Answer: Erdheim-Chester disease is a rare condition that can affect many different organs of the body. This condition, which usually affects adults, is characterized by excessive production and accumulation of histiocytes (specific cells that normally play a role in responding to infection and injury) within multiple tissues and organs. As a result, these tissues and organs become thickened, dense and fibrotic. Sites of involvement may include the long bones, skin, tissues behind the eyeballs, lungs, brain, and pituitary gland, among others. Signs and symptoms, as well as disease course, depend on the specific location and extent of involvement. Without successful treatment, organ failure can occur.
Source: GARD

Question: What are the symptoms of Erdheim-Chester disease ?
Answer: What are the signs and symptoms of Erdheim-Chester disease? The Human Phenotype Ontology provides the following list of signs and symptoms for Erdheim-Chester disease. If the information is available, the table below includes how often the symptom is seen in people with this condition. You can use the MedlinePlus Medical Dictionary to look up the definitions for these medical terms. Signs and Symptoms Approximate number of patients (when available) Abnormality of epiphysis morphology 90% Abnormality of temperature regulation 90% Abnormality of the genital system 90% Abnormality of the metaphyses 90% Bone pain 90% Diabetes insipidus 90% Hyperhidrosis 90% Increased bone mineral density 90% Multiple lipomas 90% Osteolysis 90% Osteomyelitis 90% Proptosis 90% Weight loss 90% Abdominal pain 50% Abnormality of the aortic valve 50% Joint swelling 50% Abnormality of the pericardium 7.5% Abnormality of the pleura 7.5% Anemia 7.5% Aplasia/Hypoplasia of the cerebellum 7.5% Aseptic necrosis 7.5% Congestive heart failure 7.5% Hyperreflexia 7.5% Incoordination 7.5% Nausea and vomiting 7.5% Neurological speech impairment 7.5% Nystagmus 7.5% Ptosis 7.5% Pulmonary fibrosis 7.5% Renal insufficiency 7.5% Respiratory insufficiency 7.5% Skin rash 7.5% Visual impairment 7.5% The Human Phenotype Ontology (HPO) has collected information on how often a sign or symptom occurs in a condition. Much of this information comes from Orphanet, a European rare disease database. The frequency of a sign or symptom is usually listed as a rough estimate of the percentage of patients who have that feature. The frequency may also be listed as a fraction. The first number of the fraction is how many people had the symptom, and the second number is the total number of people who were examined in one study. For example, a frequency of 25/25 means that in a study of 25 people all patients were found to have that symptom. Because these frequencies are based on a specific study, the fractions may be different if another group of patients are examined. Sometimes, no information on frequency is available. In these cases, the sign or symptom may be rare or common.
Source: GARD

Question: What causes Erdheim-Chester disease ?
Answer: What causes Erdheim-Chester disease? The specific underlying cause of Erdheim-Chester disease is not known. It is not currently categorized as a cancer, infection or autoimmune disease. It it not believed to be contagious or genetic in nature.
Source: GARD