Mixed Connective Tissue Disease, MCTD
Mixed collagenosis is a very rare autoimmune disease that combines the symptoms of several clinical pictures. These include systemic sclerosis, systemic lupus erythematosus, polymyositis and rheumatoid arthritis.
In autoimmune diseases, the immune system is directed against the body’s own structures. The reasons for this “malfunction” are not clear. However, there is probably a genetic predisposition. Mixed collagenosis can lead to skin and vascular changes, muscle and joint pain and involvement of internal organs.
The name “mixed connective tissue disease” (MCTD) comes from the fact that those affected show a mixture of symptoms from several clinical pictures. These include systemic sclerosis, systemic lupus erythematosus, polymyositis and rheumatoid arthritis.
The causes of mixed connective tissue disease are still largely unknown. However, a genetic predisposition appears to play a role in the “dysregulation” of the immune system, the activation of which then leads to the manifestation of this autoimmune disease. The symptoms are extremely varied and affect a wide range of structures and organs: the blood vessels, skin, muscles and joints – and in some cases also the heart, lungs, gastrointestinal tract or, more rarely, the nervous system.
We treat the disease with anti-inflammatory drugs such as glucocorticosteroids (“cortisone”) and other immunosuppressants. These are used to rebalance the activity of the immune system.
It is not known how many people actually suffer from mixed connective tissue disease. Experts estimate the incidence at around one to nine per 100,000 people. Women suffer from this autoimmune disease significantly more often than men. Depending on the literature, the ratio is around four to ten women to one man. The disease usually first appears between the ages of 15 and 35, sometimes only around the age of 50.
The causes of mixed connective tissue disease are still largely unknown. Due to a genetic predisposition, the immune system considers healthy body cells to be diseased or foreign and cannot distinguish between friend and foe. The immune system’s attack on the body’s own structures can damage them.
The symptoms of mixed connective tissue disease are very diverse. The reason is that a mixture of symptoms from several autoimmune diseases occurs:
These autoimmune diseases affect the soft connective tissue and hard structures such as the bones and joints. The symptoms therefore manifest themselves on the skin, muscles, joints and internal organs. They can be affected simultaneously or one after the other. The severity of the symptoms also varies from person to person.
Given the number and variety of symptoms, it is important to note that not every person with mixed connective tissue disease will develop all of the symptoms. The intensity also varies greatly from person to person.
The diagnosis of mixed connective tissue disease is a challenge, as it is very rare and requires experience with the various autoimmune diseases in order to make the diagnosis. This expertise is available at the USZ. The variety of symptoms usually makes several examinations necessary. We will first ask you about your medical history (anamnesis). The focus is on the type, duration, location and intensity of the complaints. We will also ask you about any existing illnesses, illnesses in your family or medication you are taking. This is followed by a physical examination. We palpate the muscles and joints and detect any abnormalities. We check the function, mobility and range of motion of extremities as well as the gait pattern. We also examine the skin for discoloration and other changes. We also examine the internal organs (heart, lungs, intestines, kidneys) by palpation and/or listening and check the function of the peripheral nerves.
A blood test shows whether certain blood values have changed, such as the inflammation values: C-reactive protein (CRP), erythrocyte sedimentation rate (ESR) or the leukocytes (special white blood cells). We also determine special antibodies, for example antinuclear antibodies (ANA) or specific anti-U1-snRNP antibodies. The presence or absence of certain antibodies in the blood is often very significant.
The urine test and the creatinine level in the blood show whether the kidneys are affected.
Further information is provided by imaging procedures such as X-ray examination, ultrasound examination, computer tomography (CT) or magnetic resonance imaging (MRI). Depending on the suspected organ involvement, other special examination methods may be used, for example an endoscopy of the esophagus and stomach (endoscopy), an echocardiography (heart ultrasound), a lung function test or an electroneuromyography (electrical activity of the nerves and muscles).
Sometimes we take a tissue sample (biopsy), for example from the muscle or skin. These are then analyzed by a pathologist under a microscope. Altered cells and tissue structures can thus be detected.
Based on the results of the examination, we create an individual treatment plan for each patient.
The causes of mixed collagenosis are not yet sufficiently understood. This is why you cannot prevent mixed connective tissue disease. No special measures for early detection are known either. The general rule is therefore: seek medical advice promptly if you have symptoms that do not go away and that you cannot classify.
The course and prognosis of mixed connective tissue disease cannot be generally predicted. Many affected people only have mild symptoms. However, the course can also be more severe in some patients, especially if internal organs (e.g. lungs, heart) are affected. Mixed connective tissue disease is a chronic disease that cannot be cured and can be associated with relapses. However, many symptoms can be treated well, so that for many sufferers the quality of life is hardly restricted and they can live a normal everyday life. The prognosis depends on the involvement of the organs, especially the lungs (pneumonia/fibrosis, pulmonary vascular hypertension). Early diagnosis and treatment are therefore very important.
The exchange with people who are affected by the same disease can be a great support in coping with the disease. Advice on finding a suitable self-help group is available from Selbsthilfe Zürich. Self-Help Zurich and the University Hospital Zurich are cooperation partners in the national project “Health literacy thanks to self-help-friendly hospitals”.
In mixed collagenosis, treatments are used in the same way as for the individual clinical pictures: systemic sclerosis, systemic lupus erythematosus, polymyositis and rheumatoid arthritis. We treat each affected person individually – depending on the type and severity of the symptoms, but also on the extent of the illness. In some cases, several organs are affected and the treatment is more intensive.
It also plays a role whether and how active the disease is. The doctor should have a lot of experience in the treatment of collagenoses, which is a given at a specialized center such as the USZ. We create an individual therapy concept for each patient that takes into account the individual presentation and severity of the disease. The therapy concept is then adapted on an ongoing basis.