Symptoms
The symptoms of dermatomyositis can vary greatly. However, there are characteristic symptoms that can be seen in most patients. First of all, the classic purple colouring in the area of the eyelid usually occurs; this typical skin change, which occurs mainly in the area of the eyelids and trunk, is caused by an erythema, which is usually accompanied by swelling (oedema).
An erythema is caused by the dilation of blood vessels, i.e. the veins and arteries, which leads to increased blood flow in this area of the skin. In addition to the swelling and redness, there is also a reduction in skin thickness (atrophy of the epidermis). This decrease takes place especially in the area of the finger joint extensor sides.
In addition, there is a change in the fingernails, as the small blood vessels (capillaries) can now be seen in this area. This is called telangiectasia. In addition, the patient has a permanent weakness in the musculature, especially proximal muscles are affected, i.e. the muscles in the shoulder and hip area.
For example, the patient finds it difficult to lift the arm properly. In addition to the muscle weakness, there can also be pain in the musculature, similar to the pain of a sore muscle. Another, but unnoticed, symptom is vasculitis.
This is an inflammation of blood vessels. It can lead to fever, night sweats and fatigue. Further symptoms can develop as soon as an organ such as the liver, kidney, heart, lungs or central nervous system is affected.
If the lungs are affected, for example, breathing can become difficult (dyspnoea). Due to the muscle weakness, a sad-looking facial expression can also occur (hypomimia). At a very late stage, calcium phosphate plaques accumulate in the skin (calcinosis cutis).
Diagnosis
Dermatomyositis is usually diagnosed on the basis of the recognizable symptoms. If a patient suffers from loss of strength, muscle pain, fever and a visible reddening of the skin (febrile erythema), it is most likely to be dermatomyositis. In addition, blood is taken and analysed in the laboratory.
The laboratory values then show an increase in liver enzymes (transaminases), apoproteins, LDH (lactate dehydrogenase), the enzyme aldolase and creatine kinase. In addition, antinuclear antibodies, which are directed against components of the cell nucleus, can be detected. Histological examination also reveals a decrease in the skin (atrophy of the epidermis). In addition, basal cell degeneration occurs, which means that the lowest cell layer of the skin is no longer properly recognizable as the cells perish. The electromyogram also shows an inflammation of the muscles (myositis).
Where does dermatomyositis frequently occur?
The symptoms of dermatomyositis in the area of the skin are particularly noticeable in those areas that are most exposed to sunlight. This includes not only the hands, but also the face, where dark red to blue-violet (lilac) skin discoloration (erythema) can be noticeable. These are often found in the skin area around the eyes (periorbital), in the cheek area, on the bridge of the nose, but also on the décolleté, the back and the arms.
The skin discolorations can – especially often on the eyelids – also be accompanied by slight or severe swelling, itching or even burning and pain. If the cheek area is affected, a whitish, thin rim around the mouth is usually noticeable, which is left out by the skin discoloration (perioral rim, “Shawl sign”). In addition to the characteristic skin discoloration, a change in facial features may also be noticeable, which is caused by the skin change.
Often a reduced facial expression (hypomimia) develops, from which a typical sad facial expression can result. In addition to the face, décolleté, back and arms, the hands in particular are among the areas of the body where skin changes can occur as part of an existing dermatomyositis. On the extensor sides of the fingers, i.e. the upper side of the fingers (not the side facing the palm of the hand), redness can occur – as in the face – which may also be accompanied by small raised areas or reddish, flat skin nodules (papules) (Grotton’s sign).
These so-called Grotton’s papules are often found above the finger joints, but in some cases can also extend to the back of the hand. These reddened skin and papules on the fingers can be accompanied by itching or even painful and burning sensations. Furthermore, there may also be a thickening of the cuticle and the cuticle, whereby pushing back the cuticle or touching the cuticle can also be painful (Keining sign). In rare cases, painful reduced blood circulation in the hands may occur from time to time, often triggered by cold water or cold outside temperatures (Renaud’s attacks).
