Mixed connective tissue disease (MCTD) is a rare autoimmune disorder. It’s sometimes called an overlap disease because many of its symptoms overlap with those of other connective tissue disorders, such as:
- systemic lupus erythematosus
Some cases of MCTD also share symptoms with rheumatoid arthritis.
There’s no cure for MCTD, but it can usually be managed with medication and lifestyle changes.
Since this disease can affect various organs such as skin, muscle, the digestive system and lungs, as well as your joints, treatment is targeted to manage the major areas of involvement.
The clinical presentation can be mild to moderate to severe, depending on the systems involved.
First-line agents such as nonsteroidal anti-inflammatory agents can be used initially, but some patients may require more advanced treatment with the antimalarial drug hydroxychloroquine (Plaquenil) or other disease-modifying agents and biologics.
According to the National Institutes of Health, the 10-year survival rate for people with MCTD is about 80 percent. That means 80 percent of people with MCTD are still alive 10 years after being diagnosed.
The symptoms of MCTD usually show up in sequence over a number of years, not all at once.
About 90 percent of people with MCTD have Raynaud’s phenomenon. This is a condition characterized by severe attacks of cold, numb fingers that become blue, white, or purple. It sometimes occurs months or years before other symptoms.
Additional symptoms of MCTD vary from person to person, but some of the most common include:
- pain in multiple joints
- swelling in joints
- muscle weakness
- cold sensitivity with color change of hands and in feet
Other possible symptoms include:
- chest pain
- stomach inflammation
- acid reflux
- trouble breathing due to increased blood pressure in the lungs or inflammation of lung tissue
- hardening or tightening patches of skin
- swollen hands
The exact cause of MCTD is unknown. It’s an autoimmune disorder, meaning it involves your immune system mistakenly attacking healthy tissue.
MCTD occurs when your immune system attacks the connective tissue that provides the framework for the organs of your body.
Some people with MCTD have a family history of it, but researchers haven’t found a clear genetic link.
According to the Genetic and Rare Diseases Information Center (GARD), women are three times more likely than men to develop the condition. It can strike at any age, but the typical age of onset is between 15 and 25 years old.
MCTD can be difficult to diagnose because it can resemble several conditions. It may have dominant features of scleroderma, lupus, myositis or rheumatoid arthritis or a combination of these disorders.
To make a diagnosis, your doctor will give you a physical exam. They’ll also ask you for a detailed history of your symptoms. If possible, keep a log of your symptoms, noting when they happen and how long they last. This information will be helpful for your doctor.
If your doctor recognizes clinical signs of MCTD, such as swelling around the joints, rash, or evidence of cold sensitivity, they may order a blood test to check for certain antibodies associated with MCTD, such as anti-RNP, as well as the presence of inflammatory markers.
They may also order tests to look for the presence of antibodies more closely associated with other autoimmune diseases to ensure an accurate diagnosis and/or confirm an overlap syndrome.
Medication can help manage the symptoms of MCTD. Some people only require treatment of their disease when it flares up, but others may need long-term treatment.
Medications used to treat MCTD include:
- Nonsteroidal anti-inflammatory drugs (NSAIDs). Over-the-counter NSAIDs, such as ibuprofen (Advil, Motrin) and naproxen (Aleve), can treat joint pain and inflammation.
- Corticosteroids. Steroid medications, such as prednisone, can treat inflammation and help stop your immune system from attacking healthy tissues. Because they can result in many side effects, such as high blood pressure, cataracts, mood swings, and weight gain, they’re usually used only for brief periods of time to avoid long-term risks.
- Antimalarial drugs. Hydroxychloroquine (Plaquenil) can help with mild MCTD and probably help prevent flare-ups.
- Calcium channel blockers. Medications such as nifedipine (Procardia) and amlodipine (Norvasc) help manage Raynaud’s phenomenon.
- Immunosuppressants. Severe MCTD may require long-term treatment with immunosuppressants, which are drugs that suppress your immune system. Common examples include azathioprine (Imuran, Azasan) and mycophenolate mofetil (CellCept). These drugs may be limited during pregnancy due to the potential for fetal malformations or toxicity.
- Pulmonary hypertension drugs. Pulmonary hypertension is the leading cause of death among people with MCTD. Doctors may prescribe drugs like bosentan (Tracleer) or sildenafil (Revatio, Viagra) to help prevent pulmonary hypertension from getting worse.
In addition to medication, several lifestyle changes can also help:
- Get regular exercise as much as possible. A moderate level of physical activity four to five times per week will help improve muscle strength, reduce blood pressure, and decrease your risk for heart disease.
- If you smoke, try to quit. Smoking causes your blood vessels to narrow, which can make the symptoms of Raynaud’s phenomenon worse. It also raises blood pressure.
- Try to get enough iron. About 75 percent of people with MCTD have iron deficiency anemia.
- Eat a high-fiber diet as often as you can. Trying to eat a healthy diet rich in whole grains, fruits, and vegetables can help keep your digestive tract healthy.
- Protect your hands. Protecting your hands from the cold can help reduce your chances of having a Raynaud’s phenomenon flare-up.
- Limit salt intake whenever possible. Salt can contribute to high blood pressure, which presents additional health risks for people with MCTD.
Despite its complex range of symptoms, MCTD can present as and remain a mild to moderate disease.
However, some patients may progress and develop more serious disease expression involving major organs such as the lungs.
Most connective tissue diseases are considered multisystem diseases and should be viewed as such. Monitoring major organs are an important part comprehensive medical management.
In the case of MCTD, a periodic review of systems should include symptoms and signs related to:
Because MCTD can have features of these diseases, major organs such as the lungs, liver, kidneys, and brain can be involved.
Talk to your doctor about establishing a long-term treatment and management plan that works best for your symptoms.
A referral to a rheumatology specialist might be helpful due to the potential complexity of this disease.