Mixed Connective Tissue Disease (cont.)
What is mixed connective tissue disease?
Mixed connective tissue disease, as first described in 1972, is
"classically" considered as an "overlap" of three diseases, systemic
lupus erythematosus, scleroderma, and polymyositis. Patients with
this pattern illness have features of each of these three diseases.
They also typically have very high quantities of antinuclear
antibodies (ANAs) and antibodies to ribonucleoprotein (anti-RNP)
detectable in their blood. The symptoms of many of these patients
eventually evolve to become dominated by features of one of three
component illnesses, most commonly scleroderma.
It is now known that overlap syndromes can occur that
involve any combination of the connective tissue diseases. Therefore, for
example, patients can have a combination of rheumatoid arthritis and systemic lupus erythematosus (hence, the
coined name "rhupus").
How is mixed connective tissue disease diagnosed?
Today, true mixed connective tissue disease is diagnosed when patients
demonstrate the clinical features (exam findings) of overlap
illnesses (as described above) and have high amounts of the antibodies ANA and anti-RNP in their blood.
Mixed connective tissue disease patients do not typically have
antibodies such as dsDNA, Scl70, which are particularly common in systemic lupus
erythematosus and scleroderma respectively.
How is mixed connective tissue disease treated?
The treatment of mixed connective tissue disease is based on which
features are causing symptoms. The prognosis (outlook) varies accordingly. Therapies must be targeted for each of the organ systems affected. In general, treatment is often
directed at suppressing the inflammation present in the tissues by
using anti-inflammatory and immunosuppressive medications. These
medications include nonsteroidal anti-inflammatory drugs (NSAIDs),
cortisone drugs/steroids (such as prednisone), antimalarial drugs (hydroxychloroquine), and cytotoxic drugs
(such as methotrexate, azathioprine, and cyclophosphamide). Organ
damage, such as in the kidneys, can require additional treatments
directed at high blood pressure, etc.
For the joint and muscle pains of mixed connective tissue disease, treatment options include NSAIDs, low-dose prednisone, hydroxychloroquine, and methotrexate can be helpful. Sometimes TNF blockers infliximab (Remicade), etanercept (Enbrel), or adalimumab (Humira) are considered for inflammatory arthritis. Physical therapy for certain joints is sometimes helpful. For pulmonary hypertension, medications that tend to open the arteries to the lungs are used along with blood thinning drugs and even supplemental oxygen. For interstitial lung disease, prednisone and cyclophosphamide are considered. To prevent damage to the kidneys, angiotensin converting enzyme inhibitors, such as captopril (Capoten), enalapril (Vasotec) are used, especially if blood pressure is elevated. Esophagus irritation and heartburn can be prevented by elevating the head of the bed and relieved with
omeprazole (Prilosec) or lansoprazole (Prevacid). Antacids can also be helpful. Constipation, cramping and diarrhea is sometimes caused by bacteria that can be treated with tetracycline or erythromycin.
For Raynaud's phenomenon, patients are recommended to use hand- and body-warming techniques while protecting the fingers from injury. Nifedipine (Procardia), losartan (Cozaar, Hyzaar), and nitroglycerin cream are used to dilate the constricted blood vessels. Severe RP can lead to gangrene and the loss of digits. In rare cases of severe disease, nerve surgery called "sympathectomy" is sometimes considered. In order to prevent blood vessel spasming, the nerves that stimulate the constriction of the vessels (sympathetic nerves) are surgically interrupted. Usually, this is performed during an operation that is localized to the sides of the base of the fingers at the hand. Through small incisions the tiny nerves around the blood vessels are stripped away. This procedure is referred to as a digital sympathectomy.
- Connective tissues are the framework of the cells of
the body.
- Mixed connective tissue disease is an "overlap" combination of connective tissue
diseases.
- Diagnosis of mixed connective tissue disease is supported by detecting abnormal
antibodies in the blood.
- Treatment of mixed connective tissue disease is directed at suppressing immune-related
inflammation of tissues.
For more specific information related to the individual connective
tissue diseases, please read the following articles:
References:
Koopman, William, et al., eds. Clinical Primer of Rheumatology. Philadelphia: Lippincott Williams & Wilkins, 2003.
Kelley's Textbook of Rheumatology, W B Saunders Co, edited by Shaun Ruddy, et al., 2000.
Last Editorial Review: 2/20/2008
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