dermatomyositis

Dermatomyositis: description

The term “dermatomyositis” is composed of the Greek words for skin (derma) and muscle (myos). The ending “-itis” again stands for “inflammation”. Accordingly, the term dermatomyositis describes an inflammatory disease of muscles and skin. It belongs to the group of rheumatic diseases and here to the subgroup of collagenoses (diffuse connective tissue diseases).

The inflammatory processes on the muscles and the skin damage these structures, which in turn leads to the classic symptoms. One of these is the appearance of blue-violet skin changes, which is why dermatomyositis is also called “purple disease”.

Who is affected by dermatomyositis?

In principle, dermatomyositis can affect anyone. However, there are two age peaks: Most commonly, however, adults fall ill between 45 and 65 years, with women being affected about twice as often as men. The second age peak is between 5 and 15 years (“juvenile dermatomyositis”); Here, too, girls are more affected than boys.

Overall, dermatomyositis is a rare disease. Just one in every 100,000 inhabitants in Germany gets sick each year.

Which forms of dermatomyositis are there?

Depending on the age of the patient, the course of the disease and associated diseases, physicians distinguish between different forms of dermatomyositis:

When Juvenile dermatomyositis one refers to the disease in young people. It begins acutely, and often the gastrointestinal tract is involved. In principle, the juvenile dermatomyositis does not differ from that in adulthood. However, there is one special feature: juvenile dermatomyositis is not associated with tumor diseases, and it is already associated with adult tumors.

The Adult dermatomyositis represents the classic dermatomyositis of the adult.

The Paraneoplastic dermatomyositis is a dermatomyositis that is related to, but not directly caused by, a cancer. This is the case in 20 to 70 percent of all patients. In women, paraneoplastic dermatomyositis is mainly associated with breast, uterine and ovarian cancer, in men especially with malignant tumors in the region of the lungs, prostate and digestive organs.

Sometimes the paraneoplastic dermatomyositis becomes noticeable at the same time as the tumor, in other cases it precedes or follows the cancer. In any case, it is extremely important to look for tumors if dermatomyositis has been detected.

Of the Amyopathic dermatomyositis Doctors, if the typical skin changes show up, but does not show any muscle inflammation for six months. About 20 percent of all dermatomyositis patients have this form of the disease.

polymyositis

The polymyositis is very similar to the dermatomyositis, however, there are no skin symptoms here. More details about this disease can be found in the article Polymyositis.

Dermatomyositis: symptoms

Dermatomyositis often begins acutely, but sometimes also gradually. The symptoms are characteristic but may vary in severity and composition. Typical are the skin symptoms as well as the complaints in the area of ​​the musculature. In some cases, other organs are also affected, which sometimes leads to serious complications.

At the beginning of the disease sufferers often suffer from general symptoms such as fever, fatigue, weakness and weight loss. Only in the further course then the typical complaints occur. Regarding the appearance of skin and muscle symptoms, there is no specific order. Sometimes the skin symptoms are preceded by muscle weakness, in other cases they only appear later.

Skin symptoms in dermatomyositis

Dermatomyositis is characterized by skin discolorations (erythema), which often appear dark red to blue-violet, but may also appear in a lighter red. They are preferably found on exposed skin areas on the face, neckline and arms. Especially on the eyelids can reddish swelling occur. A narrow hem around the mouth is usually free of discoloration, what physicians call “Shawl signs”.

Dermatomyositis often develops redness and sublimeness (“Gottron’s sign”) on the fingers. Another possible symptom is a thickened nail fold that hurts when pushed back (“Keining sign”).

In addition to skin discolouration, scaling of the skin may also occur on the exposed skin areas.

Muscle symptoms in dermatomyositis

In the beginning, dermatomyositis is characterized by muscle pain (especially under stress), and later by a progressive muscle weakness, which mainly affects the body (proximal) of the pelvic and shoulder girdle. Those affected are increasingly struggling with movements involving these muscles, such as lifting their legs while climbing stairs or raising arms to comb them.

In addition, dermatomyositis can also affect the eye muscles, which can result in drooping of the upper eyelid (ptosis) and squinting (strabismus).

If the pharynx and respiratory muscles are also affected, dysphagia and respiratory distress may occur.

All muscle symptoms of dermatomyositis usually occur symmetrically. If the symptoms only show on one side of the body, it is possible that another illness is behind it.

Organ involvement and complications

Dermatomyositis can affect other organs in addition to the skin and muscles, which in unfavorable cases causes dangerous complications. First and foremost here is the possible infestation of the heart and lungs.

In the heart area it can come about as a consequence to pericarditis, heart failure, a diseased enlargement of the heart muscle (dilated cardiomyopathy) or cardiac arrhythmias.

In the lungs, dermatomyositis may cause damage to the tissue followed by pulmonary fibrosis. If the constrictor fails to function properly due to dermatomyositis, the risk of inadvertently inhaling food components increases. This can cause pneumonia (aspiration pneumonia).

The Dermatomyositis can also affect the kidneys or the gastrointestinal tract, which can lead to kidney inflammation or intestinal paralysis (Darmatonie).

Overlap syndrome

In some patients dermatomyositis occurs together with other immunological systemic diseases. These include, for example, systemic lupus erythematosus, systemic sclerosis, Sjögren syndrome and rheumatoid arthritis.

Dermatomyositis: causes and risk factors

The cause of dermatomyositis is still unclear. According to the current state of research, it is an autoimmune disease:

Normally it is the task of the immune system to recognize and fight foreign structures. In this way, pathogens such as fungi, bacteria or viruses can be rendered harmless. It is important that the immune system can distinguish the body’s own from external structures.

Exactly this works in the case of autoimmune diseases but not properly. The immune system then suddenly attacks the body’s own structures because it mistakenly considers them foreign substances.

The exact mechanisms that cause such a change in the immune system are often still unknown. This also applies to dermatomyositis. But one suspects a hereditary component, so a genetic predisposition to the disease. In people with this predisposition, various factors such as infections (such as with coxsackie, influenza or retroviruses) or medications (such as antimalarials, lipid-lowering or anti-inflammatory drugs such as diclofenac) could trigger the immune system’s malfunction and thus the development of dermatomyositis:

Certain parts of the immune system, especially antibodies, target their attacks mainly against small blood vessels that supply the muscles and skin with oxygen and nutrients. This causes damage to these structures with the typical symptoms of dermatomyositis.

Related to cancer

The occurrence of malignant tumors associated with dermatomyositis is significantly increased. The exact reason for this is still unclear, though there are some assumptions (such as that a tumor produces toxins that directly damage the connective tissue). In any case, it is known that after removal of the tumor, the dermatomyositis often heals, but recurs when the cancer progresses.

Dermatomyositis: examination and diagnosis

The symptoms of dermatomyositis in the compilation are usually so typical that the doctor already develops a corresponding suspicion on the basis of the medical history and physical examination. With additional examinations, the diseases can be reliably diagnosed, in particular by the determination of laboratory values, the taking and examination of a muscle sample (muscle biopsy) and the measurement of electrical muscle activity (electromyography, EMG).

laboratory values

The collection of certain laboratory parameters can be very helpful in investigating the suspicion of dermatomyositis. In many patients, for example, the muscle enzymes in the blood are elevated, above all creatine kinase (CK), but also others such as aspartate aminotransferase (AST) and lactate dehydrogenase (LDH). This indicates a muscle disease or injury.

Other values ​​are typical of general inflammatory processes in the body, such as increased C-reactive protein (CRP) and increased erythrocyte sedimentation rate (ESR). They may or may not be elevated in dermatomyositis.

Finally, the detection of “misprogrammed” antibodies in the blood is of importance in dermatomyositis diagnostics, because these are the ones that attack the body’s own tissue. These include, for example, so-called antinuclear antibodies (ANAs), Mi-2 antibodies and Jo-1 antibodies. While the ANAs are also found in several other autoimmune diseases, the other two are relatively specific to dermatomyositis. However, they can only be found in some of those affected.

muscle biopsy

In muscle biopsy, a small piece of muscle tissue is removed and examined microscopically. Inflammatory processes or broken muscle cells can be easily identified. Muscle biopsy is the most important study for suspected dermatomyositis. However, if the clinical findings are already clear (typical skin symptoms, demonstrable muscle weakness, increased CK, etc.), the biopsy can be omitted.

Electromyography (EMG)

EMG measures muscle electrical activity. If the muscle is damaged, the examiner can detect this with the help of the EMG.

Other investigations

Imaging techniques for studying dermatomyositis are magnetic resonance imaging (MRI) and ultrasound (sonography). With their help, inflamed areas of muscle can be detected, although the MRI is more complex, but also more accurate than a muscle sonography. Both methods are also used to find suitable sites for EMG or biopsy.

In the case of organ involvement in the heart, lungs or gastrointestinal tract corresponding investigations are carried out. For example, cardiac ultrasound (echocardiography), electrocardiography (ECG), chest X-ray, or pulmonary function testing are used.

In about 30 percent of all patients dermatomyositis is associated with a tumor disease. When diagnosed, therefore, a targeted search for a cancer tumor.

Dermatomyositis: treatment

A causal therapy – ie a treatment that leads to healing – does not exist for dermatomyositis. So far, one can only try with various therapies to stop the disease and reduce the symptoms.

Drug therapy of dermatomyositis

For the treatment of dermatomyositis drugs are used that suppress the immune system (immunosuppressants). Only then can the attack of the defenses on the own body be reduced. A complete elimination of the immune system can not be achieved with it. That would not be desirable, because otherwise the body would be completely defenseless against all pathogens.

Are the first choice drug in dermatomyositis therapy glucocorticoids (“Cortisone”) such as methylprednisolone. Over the first four weeks, patients receive these drugs in high doses. Then the dose is slowly reduced until after a few months, if possible, glucocorticoids are given only every other day. Reducing the dose will reduce the risk of serious side effects.

If the administration of glucocorticosteroids is not sufficient to relieve the dermatomyositis symptoms, patients will additionally receive it immunosuppressant, which is more effective than glucocorticoids. In the first place Azathioprin is used. Other immunosuppressants used in dermatomyositis include cyclophosphamide and methotrexate (MTX). These drugs also often cause side effects that require regular monitoring and sometimes require discontinuation of the drug.

If the said remedies fail to ameliorate dermatomyositis sufficiently, it is possible to give the patient special treatment antibody (Immunoglobulins) such as rituximab. With them, the immune system can be targeted to fight where the malfunctions exist. In addition, studies are currently investigating further treatment options for their effectiveness in dermatomyositis.

Muscle training and physiotherapy for dermatomyositis

In addition to medication, physiotherapy and physical training are also useful for dermatomyositis patients. For example, strength and endurance can be increased significantly with the help of a bicycle ergometer or stepper.

During each training, the current condition of the patient is taken into account and the training intensity is adjusted accordingly. In order to achieve an effect, it is important to train regularly.

Other measures for dermatomyositis

UV radiation can aggravate the skin symptoms of dermatomyositis. Patients should therefore always pay attention to adequate sun protection.

For very pronounced localized skin symptoms, it may be useful to apply glucocorticoids externally (for example as an ointment).

Long-term use of glucocorticoids may promote osteoporosis (bone weakness). To reduce this risk, the doctor may prescribe calcium and vitamin D tablets to a patient.

In the acute phase of the disease, dermatomyositis patients should avoid physical activity or bed rest. We also recommend a balanced diet.

If a tumor disease is additionally diagnosed in dermatomyositis patients, it must be specifically treated (eg by surgery, medication, radiation). As a result, the dermatomyositis often improves.

Complications of the disease (such as in the heart or lungs area) also require special treatment.

Dermatomyositis: Disease course and prognosis

So far, dermatomyositis can not be cured. Therefore, the goal of the therapy is to alleviate the symptoms and increase the quality of life of those affected. Due to the immunosuppressive therapy (usually with glucocorticoids and an immunosuppressant) this is possible in most cases. However, the medication usually needs to be taken for one to three years, sometimes longer. In addition, the symptoms can occur again at any time or worsen.

In about 80 percent of patients dermatomyositis comes to a standstill after a maximum of five to ten years – sometimes spontaneously, sometimes thanks to the therapy. In the remaining 20 percent, the disease still exists after more than ten years.

In unfavorable cases, complications of dermatomyositis (in the area of ​​the lungs or the heart) or of a malignant tumor associated with the disease lead to death. Five years after the diagnosis Dermatomyosits 63 percent of patients still live, and 53 percent ten years later.