What is Juvenile Dermatomyositis?
Dermatomyositis is a rare illness in which the immune system mistakenly attacks the body’s own tissues, particularly muscles and skin. The cause remains unknown and it can affect both children and adults. The version found in children often involves inflammation in blood vessels throughout the body, frequent development of firm lumps under the skin known as calcinosis, red or purple bumps on the hands called Gottron papules, weakening of muscles near the trunk of the body, and a purple or red skin rash (heliotrope rash). However, while the adult form of this condition sometimes comes with an increased risk of cancer, this is not usually the case for children.
What Causes Juvenile Dermatomyositis?
Dermatomyositis is a type of inflammation illness that affects your muscles. It’s thought to be linked to your genes, as certain gene markers have been found that might make you more likely to develop the condition. One key part of dermatomyositis involves an overactive part of your immune system leading to damage in the walls of your blood vessels, causing them to become inflamed and disrupt the normal function of your muscles.
It’s also worth noting that some research suggests that certain infections might trigger the onset of this disease, as there seems to be a pattern of the condition getting worse during specific seasons. Some of these infections include:
* Parvovirus B19
* Coxsackievirus
* Streptococcus
* Enteroviruses
Apart from infections, some non-infectious factors like exposure to silica, silicone implants, and certain medications that are used to lower blood fats are also thought to play a role. Dermatomyositis tends to occur more frequently in people with a certain gene marker known as HLA-DR3.
Risk Factors and Frequency for Juvenile Dermatomyositis
The average age when this disease begins is around 7 years. Girls typically start showing symptoms earlier than boys. It usually takes about 6 months from when the first symptoms occur to when the disease is confirmed, though this can range from 5 weeks to 2 years. The disease is more prevalent in females than males. Children of white race are more likely to have it than children of other races.
- Average age of disease onset: around 7 years. Girls usually show symptoms before boys do.
- Time from onset of symptoms to diagnosis: about 6 months on average, but can range from 5 weeks to 2 years.
- The disease is more common in females than males.
- The disease is most common among children of white race.
Signs and Symptoms of Juvenile Dermatomyositis
Juvenile dermatomyositis (JDM) is a condition that commonly presents with muscle weakness and other general symptoms like tiredness, loss of appetite, irritability, pain, fever, and overall health decline. Unique skin signs are frequently observed, similar to those seen in adults with the condition. Identifying these skin signs is crucial because they can appear before the muscle symptoms. Particular signs include violet-colored patches around the eyes and Gottron papules, which are specific skin bumps seen in 30% to 70% of JDM cases.
Gottron papules often appear over joint areas of the hands, and less frequently, on the outer surfaces of elbows and knees. Other skin conditions may include painful redness around the nails with blood vessel abnormalities, excessive growth of the cuticle, facial swelling, red patches on the “V-neck” area, the front of the shoulders, and chest, and Raynaud’s phenomenon, which involves discoloration of fingers or toes. In rare instances, signs of skin vessel inflammation and sensitivity to light may occur. The muscle weakness typically progresses gradually and affects both sides of the body equally, mainly involving muscles of the pelvis and shoulders. The severity of muscle weakness can vary from mild muscle pain to severe muscle deficiency.
Children with JDM may have difficulties with daily tasks such as getting dressed, combing their hair, and climbing stairs. Over time, a condition known as calcinosis (calcium buildup in tissues) might develop, more commonly seen in children than adults. These calcium deposits can form under the skin or in deeper areas such as muscle tendons. The most common sites of calcinosis include elbows, knees, buttocks, and areas of physical trauma. The progression of calcinosis is uncertain and can lead to unpleasant cosmetic and functional complications, such as looking like cold abscesses. There is no standardized treatment for calcinosis linked to JDM, but it may decrease with early high-dose corticosteroid therapy. Another medication, called bisphosphonates, is often the first choice of treatment by experienced doctors.
When JDM interferes with muscles of the throat and esophagus, it can cause voice changes, swallowing difficulties, and breathing problems. These severe symptoms may require the patient to be admitted to an intensive care unit. Some forms of JDM, known as amyopathic, have typical skin signs but no muscle involvement. These cases carry an excellent prognosis as they usually do not have calcinosis or blood vessel complications.
In rare occurrences, heart muscles could be affected, leading to abnormal heart rhythms. A slow, progressive loss of fat usually affects the upper part of the trunk after a long course of disease. Additional symptoms could include excessive hair growth, an enlarged liver, and dark, thick skin lesions (acanthosis nigricans). It’s important to note that JDM comes with a high risk of comorbid heart and brain diseases. Lung-related issues, such as interstitial lung disease and involvement of respiratory muscles, are also common.
Testing for Juvenile Dermatomyositis
If you are suspected of having Juvenile Dermatomyositis (JDM), a disease which affects your muscles, one of the first things your doctor will do is check your blood for certain markers. The most common marker linked to JDM is increased levels of muscle enzymes in your blood. Specifically, about 75-85% of people with JDM have higher levels of a muscle enzyme called creatine kinase. The normal value is around 2000 U/L, give or take 1000. However, it’s possible to have normal levels at the start of the disease and in some forms of the disease that don’t show muscle symptoms. During your treatment, your doctor will regularly monitor your creatine phosphokinase (CPK), which is another type of muscle enzyme, to assess how effective the treatment is.
Additional tests your doctor may run include checking your ESR, or erythrocyte sedimentation rate, which measures how quickly your red blood cells settle at the bottom of a test tube (a faster rate may suggest inflammation); running a lupus profile to rule out lupus; and checking for myositis-specific antibodies which could indicate inflammation in your muscles.
A test known as an electromyogram can also be useful. In this test, small electrodes are inserted into your muscles to measure their electrical activity. This can generally show a myogenic pattern, meaning the problem is within the muscle itself. But the most definitive way to confirm JDM diagnosis is through a muscle biopsy, where a small sample of your muscle tissue is removed and examined under a microscope.
Some of the things the doctor will look for in your muscle tissue are signs of muscle fiber degeneration, inflammatory cells, perivascular inflammatory infiltrate which are inflammation cells around blood vessels, and sometimes tiny blood clots within your blood vessels. A very specific characteristic they may find is called perifascicular atrophy, which is a thinning of muscle fibers around bundles of nerve fibers.
Non-invasive imaging techniques like magnetic resonance imaging (MRI) can also be helpful in confirming JDM. This will guide your doctor in deciding where to take the biopsy from for better sensitivity. The most common abnormality seen on the MRI is muscle edema, which is swelling in the muscles. The swelling is usually around your torso and is symmetric, but it can sometimes be localized and in your extremities. High signal intensity on the MRI could be linked to a more severe, long-term disease course.
Treatment Options for Juvenile Dermatomyositis
Systemic corticosteroids, a type of medication often used to reduce inflammation, are the main treatment for Juvenile Dermatomyositis (JDM), a childhood disease affecting the skin and muscles. However, there is no agreement yet on the exact dosage and treatment methods. Initially, doctors usually recommend an amount of medication based on the child’s body weight. If the child has trouble with their digestive system, they might receive the medication through an IV, or a small tube inserted into a vein. This may be because inflammation has affected blood vessels in their gut, leading to problems absorbing food. Usually, treatment with steroids is lengthy and needs to be reduced gradually to achieve remission, or a lull in symptoms. Alongside the medication, it’s important children with JDM follow certain lifestyle methods and take daily supplements of calcium and vitamin D to strengthen their bones, as they face a high risk of developing osteoporosis, a condition that weakens bones and makes them prone to fracture.
If there’s no improvement with steroid therapy or the child experiences severe side effects, doctors might decide to try a different medicine given under the skin called methotrexate. Combining methotrexate and corticosteroids can be a good way to manage the condition without causing major side effects. Another medicine, hydroxychloroquine, could also be a new approach to treating JDM. For children with severe forms of the disease that are hard to treat, more specialized drugs (infliximab, rituximab) may be used. Confirming the safety of these drugs in children requires more controlled, randomized clinical trials.
In some cases called “amyopathic JDM”, where symptoms aren’t present or are less severe, doctors generally avoid treatments. These patients usually continue to have no symptoms even after many years. Physical therapy is an important part of managing JDM; it should start as soon as symptoms are managed and aims to rebuild muscle strength and prevent stiff joints.
Occupational and speech therapy is used for children who have difficulty swallowing, a condition called dysphagia. These therapies teach the child and their family how to adjust food consistency and the position of the chin, head, and tongue for easier, safer swallowing.
What else can Juvenile Dermatomyositis be?
Some medical conditions that could be suspected based on the patient’s symptoms are:
- Myositis (inflammation of the muscles)
- Lupus (an autoimmune disease which causes inflammation to various parts of the body)
- Raynaud’s phenomenon (a condition causing discoloration of the fingers and toes)
- Scleroderma (a rare disease affecting the skin and other organs)
- Eczema (a skin condition causing itchy, red patches)
- Psoriasis (a skin disease causing red, scaly patches)
- Tinea (a type of fungal infection commonly known as ringworm)
- Muscular dystrophy (a group of genetic diseases that cause muscle weakness and loss of muscle mass)
What to expect with Juvenile Dermatomyositis
The progression of this condition can vary greatly and is hard to predict. The disease may occur in a one-time episode, recurring episodes, or persist over a long period. However, recent advancements in treatment options have greatly improved the outcome for many patients. Prompt treatment and consistent monitoring can help manage the disease more effectively.
Despite these advancements, in developing countries, the mortality rate remains high. The primary causes of death often include severe muscle weakness, additional infections, gastrointestinal inflammation that could cause bowel tear, heart failure, and breathing difficulties.
Calcinosis cutis, which is the formation of calcium deposits in the skin, happens in about 30% of the patients, leading to significant health issues. These calcium deposits can cause not just cosmetic concerns but can also lead to pain and functional limitations. Moreover, they can lead to stiff joints, skin ulcers, and even nerve entrapment.
Before steroid treatment became available, one in three patients would get better on their own, one in three would have a long-lasting disease course, and one in three would unfortunately die from the disease.
It’s important to note that juvenile dermatomyositis (JDM), unlike the adult version, is usually not linked to the development of cancers.
Possible Complications When Diagnosed with Juvenile Dermatomyositis
Dermatomyositis can be accompanied by several complications:
- Difficulty in swallowing (Dysphagia); this can happen if the muscles that help swallow, found in the esophagus, are affected. This can result in weight loss and undernutrition.
- Aspiration pneumonia; problems with swallowing can cause food particles, liquids or saliva to be inhaled into the lungs.
- Breathing problems; if muscles in the chest or around the ribs are affected, it can lead to shortness of breath (dyspnea).
- Calcium deposits; as the disease worsens, calcium can build up in the muscles, connective tissues, and skin.
Preventing Juvenile Dermatomyositis
If your child has Juvenile Dermatomyositis (JDM), a rare disease that causes muscle inflammation and skin rash, it might negatively affect your family’s overall happiness and well-being. As such, it’s important to consider getting mental health support for both your child and yourselves as parents during this difficult time.