Brief overview
- What is dermatomyositis? A rare inflammatory muscle and skin disease that is one of the rheumatic diseases. Also called purple disease because of the often purple skin lesions.
- Forms: Juvenile dermatomyositis (in children), Adult dermatomyositis (mainly in women), Paraneoplastic dermatomyositis (associated with cancer), Amyopathic dermatomyositis (skin changes only).
- Symptoms: Fatigue, fever, weight loss, later muscle pain, weakness in the shoulder and pelvic area, possibly drooping eyelid or squint, possibly shortness of breath and difficulty swallowing, scaly skin discoloration, swelling and redness in the eye area. Possible complications (such as cardiac arrhythmias, pulmonary fibrosis, kidney inflammation).
- Causes: Autoimmune disease whose causes are not fully known. Possibly genetic and triggered by factors such as infections or medications.
- Treatment: Medication (such as cortisone), muscle training and physiotherapy.
- Prognosis: Treatment can usually significantly relieve or completely eliminate symptoms. However, mild muscle weakness often remains. Complications and concomitant tumor disease can worsen the prognosis.
Dermatomyositis: Description
The term “dermatomyositis” is composed of the Greek words for skin (derma) and muscle (myos). The suffix “-itis” means “inflammation”. Accordingly, dermatomyositis is an inflammatory disease of muscles and skin. It belongs to the group of inflammatory rheumatic diseases and here to the subgroup of collagenoses (diffuse connective tissue diseases).
Dermatomyositis: Forms
Depending on the age of the patient, the course of the disease and associated diseases, physicians distinguish between different forms of dermatomyositis:
Juvenile dermatomyositis.
This refers to dermatomyositis in young people. It mainly affects children in their seventh and eighth year of life, with girls and boys suffering from the disease at about the same rate.
Juvenile dermatomyositis begins acutely and often also affects the gastrointestinal tract. One important difference from dermatomyositis in adults: The juvenile variant is never associated with tumor disease, which, in contrast, is often the case in adult dermatomyositis patients.
Adult dermatomyositis
This is the classic adult-onset dermatomyositis. It predominantly affects women between the ages of 35 and 44 and between 55 and 60.
Paraneoplastic dermatomyositis
Paraneoplastic dermatomyositis occurs especially in the age group of 50 years and older. Dermatomyositis is most frequently associated with the following cancers, depending on gender:
- Women: Breast cancer, uterine cancer, ovarian cancer
- men: lung cancer, prostate cancer, cancer of the digestive organs
Amyopathic dermatomyositis
Doctors speak of amyopathic dermatomyositis when typical skin changes occur, but no muscle inflammation can be detected for six months. About 20 percent of all patients develop this form of dermatomyositis.
Dermatomyositis: frequency
Dermatomyositis is a very rare disease. Between 0.6 and 1 in 100,000 adults worldwide develop it each year. Juvenile dermatomyositis is even rarer – around the globe, about 0.2 in 100,000 children are affected annually.
Polymyositis
Dermatomyositis: symptoms
Dermatomyositis usually begins insidiously and usually develops within three to six months. Initial symptoms, which are still non-specific, include fatigue, fever, weakness and weight loss. Many sufferers also initially experience muscle pain similar to that associated with sore muscles. Later, muscle weakness and skin changes complete the clinical picture.
Muscle complaints do not always make themselves felt first and skin changes later – the order in which the symptoms appear can vary from patient to patient.
Rarely, other organs are affected by the disease in addition to muscles and skin. If the heart or lungs are affected, serious complications can arise.
Skin symptoms of dermatomyositis
Reddish swollen eyelids are also typical dermatomyositis symptoms – as is a narrow line around the mouth that remains free of discoloration (Shawl sign).
Other typical signs include redness and raised areas on the skin over the finger joints (Gottron’s sign) and a thickened nail fold that hurts when pushed back (Keining’s sign).
Muscle symptoms of dermatomyositis
Muscle pain is typical of incipient dermatomyositis. They occur preferentially during exertion. If the disease progresses further, increasing muscle weakness develops, which is particularly noticeable proximally, i.e. in the pelvic and shoulder girdles. As a result, sufferers find it difficult to perform many movements involving the leg and arm muscles, such as climbing stairs or combing their hair.
The eye muscles can also be affected. This is manifested, for example, by a drooping upper eyelid (ptosis) or squinting (strabismus).
The muscle symptoms of dermatomyositis usually occur symmetrically. If the symptoms only appear on one side of the body, another disease is probably behind it.
Organ involvement and complications
In addition to the skin and muscles, dermatomyositis can also damage other organs, which can lead to dangerous complications:
- Heart: Here, dermatomyositis can cause, for example, pericarditis, cardiac insufficiency, abnormal enlargement of the heart muscle (dilated cardiomyopathy), or cardiac arrhythmias.
- Lungs: pulmonary fibrosis may result from damage to lung tissue. If dermatomyositis affects the swallowing muscles, the risk of accidentally inhaling food particles increases, which can cause pneumonia (aspiration pneumonia).
Overlap Syndrome
In some patients, dermatomyositis occurs together with other immunologic systemic diseases, for example, systemic lupus erythematosus, systemic sclerosis, Sjögren’s syndrome, or rheumatoid arthritis.
Dermatomyositis: Causes and risk factors
The causes behind dermatomyositis are not yet fully understood. Current research assumes that it is an autoimmune disease.
Autoimmune disease
Normally, the immune system can unerringly distinguish between the body’s own and foreign structures: Foreign ones are attacked, while the body’s own are not. But this is exactly what does not work properly in autoimmune diseases – the immune system suddenly attacks the body’s own structures because it mistakenly believes them to be foreign substances.
Certain antibodies then begin to attack those blood vessels that supply muscles and skin with oxygen and nutrients. The structures damaged in this way subsequently trigger the typical symptoms of dermatomyositis.
Connection with cancer
The likelihood of paraneoplastic dermatomyositis – that is, dermatomyositis with a link to tumor disease – is significantly increased, especially in people aged 50 and older. The exact reason for this is still unclear, although there is some conjecture – such as that a tumor produces toxins that directly damage connective tissue.
In any case, it is known that dermatomyositis often heals after the tumor has been removed, but recurs if the cancer progresses.
Dermatomyositis: examinations and diagnosis
Blood test
Certain blood values help in the diagnosis of dermatomyositis:
- Muscle enzymes: Elevated levels of muscle enzymes such as creatine kinase (CK), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH) indicate muscle disease or damage.
- C-reactive protein: C-reactive protein (CRP) is a non-specific inflammatory parameter. Elevated levels therefore indicate inflammatory processes in the body.
- Blood sedimentation rate (ESR): Increased blood sedimentation can also generally indicate inflammation in the body.
- Auto-antibodies: Antinuclear antibodies (ANAs), Mi-2 antibodies and anti-Jo-1 antibodies attack the body’s own tissue and are often (but not always) detectable in dermatomyositis.
While ANAs are also present in quite a few other autoimmune diseases, the other two autoantibodies are relatively specific to dermatomyositis (and polymyositis).
Muscle biopsy
A biopsy is not necessary if the clinical findings are already clear. This is the case, for example, if the patient has the typical skin symptoms and demonstrable muscle weakness.
Electromyography (EMG)
In electromyography (EMG), the physician measures electrical muscle activity with the aid of attached electrodes. The results can be used to determine whether the examined muscle is damaged.
Other examinations
Inflamed muscle structures can be visualized using magnetic resonance imaging (MRI) and ultrasound (sonography). Although MRI is more complex, it is also more precise than sonography. Both methods are also used to find suitable sites for an EMG or a biopsy.
Because dermatomyositis is often associated with cancer (in adults), tumors are also specifically sought during diagnosis.
Dermatomyositis: Treatment
Treatment of dermatomyositis usually consists of taking medication, usually for several years. This can counteract progression of the disease, alleviate symptoms and improve the quality of life of those affected. Muscle training and physiotherapy also make a contribution.
Drug therapy for dermatomyositis
If glucocorticoids are not sufficient to relieve the symptoms, other immunosuppressants such as azathioprine, cyclophosphamide or methotrexate (MTX) are used. They dampen the immune system to such an extent that it no longer targets the body’s own structures. However, the immune system cannot be completely eliminated. And this is a good thing, so that the body continues to be protected against pathogens.
If the above-mentioned remedies cannot sufficiently improve dermatomyositis, treatment with special antibodies (immunoglobulins) such as Rituximab is an option. These fight the immune system exactly where it acts incorrectly.
Muscle training and physiotherapy for dermatomyositis
Physiotherapy and physical training can support the success of treatment. Strength and endurance can be significantly increased, for example, with the help of a bicycle ergometer or stepper.
Other measures for dermatomyositis
In paraneoplastic dermatomyositis, the tumor disease must be specifically treated, for example, by surgery, chemotherapy and/or radiotherapy. Subsequently, the dermatomyositis often improves.
Complications, for example in the heart or lungs, also require special treatment.
Further measures and tips for dermatomyositis:
- UV radiation can worsen skin changes. Dermatomyositis patients should therefore protect themselves sufficiently from the sun (suntan lotion with a high sun protection factor, long pants, long-sleeved tops, etc.).
- Long-term use of glucocorticoids increases the risk of osteoporosis (bone weakness). Therefore, as a preventive measure, the doctor may prescribe taking calcium and vitamin D tablets.
- In the acute phase of the disease, dermatomyositis patients should avoid physical activity or bed rest.
- A balanced diet is also recommended.
In most cases, immunosuppressive therapy can alleviate or even completely eliminate the symptoms. However, a pre-existing mild muscle weakness may remain. In addition, symptoms may recur at any time.
In some patients, treatment may not relieve the symptoms but may at least halt the disease. In others, however, the disease progresses unabated despite treatment.
Risk factors for severe courses
Advanced age and male gender favor a severe course of the disease. The same applies if the heart or lungs are also affected. Concomitant cancer is also considered a risk factor for a severe course of dermatomyositis. Life expectancy may be reduced in such cases.
