What is Pediatric MCTD?
Mixed connective tissue disease (MCTD) is a rare disease in children. It has features of several conditions including arthritis, scleroderma, dermatomyositis and lupus. A blood test showing an antibody called RNP is needed to help make the diagnosis.
MCTD is a type of autoimmune disease. Normally, the immune system protects the body from infections. In autoimmune diseases, the immune system mistakenly attacks the body’s own healthy tissues. This can cause swelling (inflammation) and, if not controlled, damage to organs.
Who Gets Pediatric MCTD?
- Pediatric MCTD starts in children under the age of 16, but can continue into adulthood.
- MCTD is three times more frequent in girls than boys.
- MCTD is one of the rarest rheumatic diseases in children.
What Causes Pediatric MCTD?
We do not know the cause of MCTD. A number of factors have been researched, but no single factor has been found.
One theory is that development of MCTD requires a blend of environmental factors and genetic risk factors, where children who are genetically at risk may develop MCTD after being exposed to something in the environment. Instead of stopping after fighting the virus, the immune system keeps attacking the body’s own tissues.
MCTD does not usually run in families, though certain genes may make a child more likely to have MCTD.
MCTD is not contagious (you cannot catch it from someone else) and there is no treatment to prevent it. Also, you cannot prevent MCTD by getting a vaccine.
What are Signs and Symptoms of Pediatric MCTD?
MCTD often begins with fever, decreased energy, and weakness. The symptoms can range from mild to life-threatening.
Pediatric MCTD can go into periods of remission where symptoms are not present. The two most common findings in MCTD at the time of diagnosis are arthritis and Raynaud's phenomenon. Arthritis is painful, swollen and tender joints, loss of motion, and heat or redness. Raynaud's is a sudden, reversible sequence of skin color changes (pale, blue and / or red). This often affects fingers and toes, and may happen after being in the cold. Raynaud's may also occur in other inflammatory connective tissue diseases such as scleroderma.
Pulmonary hypertension is not common, but is a very dangerous complication of pediatric MCTD. It most often develops slowly and silently. Its symptoms, like shortness of breath and chest pain, must be reported to your child’s doctor right away.
The most common disease characteristics in pediatric MCTD and the percent of children who may have them are:
| Disease characteristics | Affected |
|---|---|
| Arthritis | 93% |
| Raynaud's phenomenon | 85% |
| Muscle disease | 61% |
| Fever | 56% |
| Lung disease (Often "silent" at first) | 40-50% |
| Thickened skin of scleroderma | 49% |
| Dry eyes and dry mouth | 36% |
| Rash of lupus (SLE) | 33% |
| Rash of juvenile dermatomyositis | 33% |
| Kidney disease | 26% |
| Central nervous system disease | 23% |
| Heart disease | 15% |
| Pulmonary hypertension | 7% |
How is Pediatric MCTD Diagnosed?
The diagnosis of pediatric MCTD is made by a careful review of a person's medical history, physical exam, lab tests (blood and urine) and imaging. It may take months or even years for doctors to conclude that evolving symptoms represent pediatric MCTD. There is no single test that can prove your child has MCTD. Since all people with MCTD have RNP antibodies, this is required for diagnosis. RNP is a nuclear protein in the blood that some experts believe could be involved in causing the disease. When a child is suspected of having MCTD, pulmonary function tests will be done. This requires breathing into a tube. An abnormal result suggests lung involvement.
How is Pediatric MCTD Treated?
There is no known cure for pediatric MCTD, but there is effective treatment that can reduce or stop symptoms. This allows children with MCTD to lead healthy, productive lives.
There is no specific treatment for MCTD. Treatment will be tailored to a child’s pattern of symptoms. Over time, some patients develop mild arthritis and only need symptom relief. Patients who develop lung disease will need steroids and other immune-suppressing medicines.
Raynaud's phenomenon responds well to protection from the cold, such as wearing mittens. If warming techniques alone are not enough, some children with Raynaud's may need medications, like calcium channel blockers.
Medicines used to treat children with MCTD include.
NSAIDs (Nonsteroidal Anti-Inflammatory Drugs)
Medications like ibuprofen, naproxen, meloxicam and celecoxib are used to control the mild arthritis often seen in MCTD. Up to 1/3 of children get adequate disease control with the use of NSAIDs alone. Children tolerate these drugs very well. They rarely cause side effects like upset stomach.
Prednisone
Prednisone is a medication commonly used in MCTD and is a type of steroid. You may hear this referred to as corticosteroids or glucocorticoids as well. Other types of steroids that may be used are methylprednisolone or prednisolone. Prednisone (or one of the other steroids) may be used to treat severe arthritis that does not respond to NSAIDs. It is also used to treat pulmonary hypertension.
Prednisone works quickly to calm the immune system and control inflammation. This medication is like cortisone, a natural hormone made by our bodies. At first, high doses of steroids may be given to quickly reduce swelling in the joints, muscles, skin or lungs. As your child improves, the steroid dose will be reduced over time to prevent side effects that are common at higher doses. Side effects depend on both the dose and length of therapy.
Common side effects include weight gain, increased appetite, increased risk for infections and facial swelling. Over a long period of time, the drug may cause decreased bone calcium content, cataracts, high blood pressure and a slowed growth rate. The doctor will lower the dose as soon as possible to decrease the risk of side effects, while keeping the disease under control.
Hydroxychloroquine (brand name Plaquenil®)
This antimalarial drug is used to treat MCTD and also lupus. Hydroxychloroquine is taken as a pill once a day.
Hydroxychloroquine does not usually have serious side effects, but some children may get an upset stomach. About 1 in every 3,000-5,000 people who take hydroxychloroquine will get pigment in the retina of the eye. If this is allowed to progress, it can interfere with a person's eyesight. For this reason, an ophthalmologist (eye doctor) needs to check your child's eyes once a year while your child is taking this medicine. If the eye doctor finds any pigment build up, hydroxychloroquine will be stopped before any visual problems develop.
Immunosuppressives
For patients with more severe symptoms like lung, kidney or central nervous system disease, drugs called immunosuppressives may be used. These drugs calm the immune system by preventing new autoimmune cells from being formed.
What is the Long-Term Outlook for Children With MCTD?
Pediatric MCTD can be treated. The long-term outcome depends on a child’s disease characteristics and response to medicines. So, the outcome varies and can’t be predicted. Some children achieve remission and may stop their medicines. But other children may have active disease for many years. Some may have more severe symptoms than others. Despite the challenges children with MCTD and their families face, most grow up to lead an active, productive life.
