Diagnosis and Treatment
Because it is so rare, Erdheim-Chester disease is often difficult to diagnose. Patients may go for months and even years after symptoms start until they are properly diagnosed. This disease is sometimes mistaken for Langerhans cell histiocytosis, and a thorough workup including biopsy is necessary to tell the difference between the two diseases. There are also differences in the appearance of the bone lesions on x-ray, but x-ray alone is not diagnostic.
A biopsy involves taking a small piece of the affected tissue so that it can be viewed under a microscope by a pathologist. If the cells in the tissue have specific characteristics, the diagnosis of ECD can be made. One of these characteristics is the presence of foamy histiocytosis with signs of inflammation and something called Touton-type giant cells. Unlike LCH, the cells in Erdheim-Chester disease do not have Birbeck granules or stain positively for something called the S-100 antigen or CD1a. ECD cells stains positively for the same proteins as JXG, that is CD68 and factor XIIIa.
Once the diagnosis is made, the extent of disease should be established. Further diagnostic testing will depend on the individual case and may include testing similar to that used for Langerhans cell histiocytosis:
- Physical examination, history of symptoms, past illnesses, etc.
- Blood tests: To evaluate function of the internal organs such as heart and kidneys.
- Neurological examination: Testing of ability to walk, muscle testing, coordination, etc.
- X-ray: This can be performed of the lungs or the bones to determine if there are abnormalities.
- Bone scan: This is a type of x-ray that looks for bone lesions. A small amount of radioactive material is injected into a vein, collects in any abnormal parts of the bones, and is shown on a scanner.
- CT scan: This is an x-ray that takes a number of detailed pictures at different angles inside the body. Dye may be injected into a vein or swallowed to help find any abnormalities.
- MRI: This is another kind of x-ray that takes a number of detailed pictures inside the body. A substance called gadolinium may be injected into a vein.
- PET scan: A small amount of radioactive sugar is injected into a vein, and diseased cells show up brighter on the scanner.
- Ultrasound: This is a kind of x-ray procedure where high-energy sound waves are bounced off organs and tissue and make echoes, which form a picture of the internal body.
- Electrocardiogram: This is a tracing of the heart rate and rhythm.
- Echocardiogram: This uses sounds waves to provide pictures of the heart in order to evaluate blood flow and heart function.
The severity of the disease is determined by how widespread the involvement occurs outside of bone and whether internal organs are affected.
Because this is a very rare disease, no large studies have been performed, and no treatment plan has been established that is widely accepted. However, various treatments have been used by individual doctors with different levels of success. These include:
- Systemic corticosteroids
A kind of drug based on hormones that work to reduce inflammation in the body.
The purpose of this treatment, also known as interferon, is to restore the ability of the immune system to fight off infections. It is usually given as an injection.
Drugs usually given in the vein to control the over-production of histiocytes. This may include vinblastine (Velban), vincristine (Oncovin), cyclophosphamide (Cytoxan), doxorubicin (Adriamycin), and cladribine (2CdA). Other drugs such as methotrexate, Gleevec, Tamoxifen, Imuran, and CellCept have also been used. New therapies which target the chemicals (cytokines) produced in excessive amounts in patients with ECD have been tested in a very small number of patients with ECD and may prove beneficial in the future but would be considered experimental at present.
This involves the use of high-energy rays to destroy rapidly increasing histiocytes.
This may be used to decrease symptoms caused by masses of histiocytes.
It is important to remember that while these treatments may control the symptoms and growth of the disease, to date, there is no known “cure” for Erdheim-Chester.