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Medical Author:

William C. Shiel Jr., MD, FACP, FACR

William C. Shiel Jr., MD, FACP, FACR

Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

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Medical Editor:

Dennis Lee, MD

Dennis Lee, MD

Dr. Lee was born in Shanghai, China, and received his college and medical training in the United States. He is fluent in English and three Chinese dialects. He graduated with chemistry departmental honors from Harvey Mudd College. He was appointed president of AOA society at UCLA School of Medicine. He underwent internal medicine residency and gastroenterology fellowship training at Cedars Sinai Medical Center.

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In this Article

• What are connective tissues?
• What diseases characteristically affect connective tissue?
• What is mixed connective tissue disease?
• How is mixed connective tissue disease diagnosed?
• How is mixed connective tissue disease treated?
• Mixed Connective Tissue Disease At A Glance
• Find a local Rheumatologist in your town
• Mixed Connective Tissue Disease Index

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").

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.

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:

• Systemic Lupus Erythematosus
• Rheumatoid Arthritis
• Scleroderma
• Polymyositis

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.