Dermatomyositis in children (Juvenile dermatomyositis, JDM) is a chronic, systemic connective tissue diseases with skin and muscle inflammation in children (before 16-18 years of age). The rheumatic inflammation of the skin and muscles causes characteristic symptoms. Special blood tests usually show typical signs of the disease. Dermatomyositis in children has a different course than dermatomyositis in adults. The disease is so rare that one sees only 2-4 cases annually per million children (incidence) (reference: Meyer A, 2015), but the cause is unknown.
Symptoms of juvenile dermatomyositis
Fever, fatigue, weight loss can occur from early in the course.
Skin symptoms are common, often with typical red-blue-purple staining and some swelling over the stretching side of knuckles on hands (Gottron's sign / papels) and at the extensor side of elbows and knees. Some children get purple upper-eyelid discoloration (Heliotropic eczema). The areas around the eyes may also swell.
Calcium storage (calcinosis) under the skin is characteristic but does not occur in all (10-30%).
Muscle weakness. Fatigue and exhaustion along with failure of muscle strength are common symptoms. Muscle pain may occur, but not in all (amyopathic dermatomyositis). Thigh muscles are most often attacked. Symptoms of muscle weakness can include difficulty getting up from the floor or chair, going up stairs and slopes. In severe attacks, the pharyngeal muscles may also be so weak that normal swallowing is not possible.
Lungs. Some people get dry cough and heavy breathing with exertion if the lungs are also attacked.
Medical history charts typical symptoms in the skin, muscles and other organs (see above), as well as fever, weight loss and the general condition in general.
Clinical Do a general examination that includes examination of the skin and muscles, heart, lungs and blood pressure. Muscle strength can be tested according to a schedule, often by experienced physiotherapists.
Blood tests may show elevated signs of inflammation (CRP, SR), but not necessarily. Similarly, creatine kinase (CK), LD and AST do not need to be elevated when the muscles are little attacked. «Rheumatism tests» (Immunological tests) are seen in 60–95%.
Imaging with X-ray, ultrasound or MRI can detect calcinosis. Muscle inflammation (myositis) can be shown by MRI examination (most often of the thigh muscles). Difficulty swallowing is shown by X-ray of the esophagus with ingestion of contrast medium. CT of the lungs can be done to assess if the lungs are affected.
Tissue sample (biopsy) can be crucial to the diagnosis when muscles are attacked. The sample is taken in anesthesia and often from the thigh muscle. On microscopic examination, "perimysial infiltration" is present in dermatomyositis, which is more common than polymyositis ("endomysial infiltrations"). Immune-mediated necrotizing myopathy is a very rare type that shows necrosis in myofibers, but with minimal inflammatory cell infiltrates.
Juvenile dermatomyositis is diagnosed on the basis of symptoms and examination findings (see above).
Similar conditions / differential diagnoses
Other muscular diseases with increased CK in children:
Muscular dystrophies is also discussed on a separate page. Becker's muscular dystrophy is a milder form similar to Duchenne muscular dystrophy (see below). Duchenne muscular dystrophy is the most common muscle disease in childhood. It is inherited X-bound (boys are attacked). Disease onset most often at 2-3 years of age. The boys can not run. Thickened calf muscles. Dystrophy myotonica leads to reduced ability for muscle relaxation. Often cognitive changes (attention, memory, concentration). Emery-diffusible muscular dystrophy is often X-linked (boys are attacked) and is characterized by tightness in the elbows and stiffness in the back. Shoulder-hip muscular dystrophies consists of about 30 subgroups that are characterized by muscle weakness in the shoulders and hips.
Myasthenia leads to increased physical fatigue with gradual development during childhood.
Spinal muscle atrophy may be present in «atypical myositis»,
Antifosfolipid syndrome assessed by fever episodes, elevated CRP over time, livedo reticularis, and stroke at a young age.
Behcet's disease causes recurrent sores in the mouth and abdomen.
Mitochondrial Disease occurs as mitochondrial myopathy, encephalomyopathy, lactate acidosis, stroke-like symptoms (MELAS), Myoclonic Epilepsy with Ragged Red Fibers»(MERRF) with“ Ragged Red Fibers ”are clumped diseased mitochondria in tissue sample (biopsy), short stature, hearing loss, lactate acidosis, intolerance to physical exercise.
Sarcoidosis with swollen lymph nodes also in the lungs, skin changes and muscle weakness rarely occur. Also Wilson's disease which attacks nerves, brain and liver can resemble muscle disease and is very rare.
Interdisciplinary treatment where the physiotherapist adapts and follows up on an exercise and activation program is important in case of muscle disease.
Medications for juvenile dermatomyositis are important to fight the rheumatic inflammation initially and to keep the disease under control throughout the course. Often, the inflammation stops within a few years, but treatment and follow-up over several years is necessary.
Cortisone. Drug treatment with cortisone in the form of Prednisone tablets combined with other immunosuppressive drugs are usually required. The cortisone dose often needs to be high to begin with, but the dose is gradually reduced. The side effects include weight gain and growth reduction, but are transient.
Other medicine unless side effects take over for cortisone later in the course: methotrexate, Azathioprine and biological drugs. Against calcinosis (calcium under the skin), no medication has shown a safe effect.
Follow-up done in collaboration with a specialized center. In the process, cortisone medication is gradually tapered off and discontinued first. If the disease remains peaceful, other medications can be gradually discontinued after a further approx. one year.
No studies indicate that a particular diet or supplements of vitamins, trace elements or otherwise have an effect on juvenile dermatomyositis. In the case of long-term illness and treatment, regular meals with a well-balanced diet are important to prevent the lack of proteins, vitamins, calcium and other minerals. During Prednisolone (cortisone) treatment, calcium and calcium supplements are given Vitamin D to reduce the risk of osteoporosis (osteoporosis.). More about Diet in rheumatic disease here (Bindevevssykdommer.no)
- Li D, 2019
- Enders FB, 2017
- Gupta R, 2019
- Differential Diagnostics Aden P, 2017 (Musculoskeletal Disease Disorders)
- Grans Compendium in Rheumatology