Manifestations cutanées des connectivites mixtes (ou connectivite mixte) (CM) (Mixed Connective Tissue Disease (MCTD)) (Pour les professionnels)

• One of the autoimmune systemic diseases which have extensive skin manifestations is mixed connective tissue disease or MCTD. This disorder is a combination of other autoimmune diseases such as lupus erythematosus, systemic sclerosis and polymyositis. The cause of this disorder is not completely known but is stipulated to be an effect of one’s immune system attacking his or her human leukocyte antigens and other cells. It is also genetic (runs in families).

So how does one know whether he or she has mixed connective tissue disease just by looking at the skin?

• Patients with MCTD may present with discoloration of the fingers, toes, and occasionally other areas, a sign known as Raynaud phenomenon.
• When one examines the dorsum of the hands, one notes swelling and sausage-shaped fingers.
• If you take a look at the nail folds, you can see abnormal capillaries or small blood vessels there. This is a sign of small vessel vasculitis, which in turn gives rise to leg and foot gangrene and leg or foot ulcers.
• In some people with MCTD, there may be reddish plaques like that in patients with lupus erythematosus. One can also have balding, redness of the face, skin pigment changes and nail changes. Also, painful skin nodules may appear on the hands and elbows.

Are the clinical features only to be found on the skin ?

• Systemically the person may also experience headaches and easy fatigability. People with MCTD also suffer from joint pain and arthritis with morning stiffness of the joints. There may also be muscle pain and weakness. One may also have difficulty in swallowing, constipation, diarrhea and malabsorption. There may also be lung diseases, kidney diseases, and heart diseases in a few cases.

How is the diagnosis confirmed ?

• When visiting a doctor who suspects MCTD, he may then request laboratory tests such as a complete blood count, liver and kidney function tests, muscle enzyme tests and others ANA (ANti Nuclear Antibodies), ENA (Extracted Nuclear Antibodies)…). Tests on urine (urinalysis) may also be done.
• Anemia, decrease in platelet count and (thrombopenia) a decrease in white blood cell count (leukopenia) are some expected changes in the complete blood count. Urinalysis may reveal protein and red blood cells in the urine. Elevated creatinine, urea, aldolase and creatine kinase levels may also occur.
• Following diagnostic suspicion, specialists further evaluate and manage. Specialists may include Dermatologists, Immunologists, Internist, Rheumatologists…A dermatologist evaluates the skin lesions while an internist and other specialists may evaluate organ involvement.

How is the condition treated ?

• The treatment for this disorder involves the use of corticosteroids or immunosuppressives if the severity of disease justifies it.
• NSAIDs or pain reliever drugs may provide symptomatic relief for arthralgia, myalgia, edema, and tenderness.
• Steroids applied to the skin in the form of creams and ointments reduce inflammation and prevent the proliferation of this disease.

What are the implications of having the disease?

• It is said that one of the possible dreadful complications of MCTD is cancer. 10% of the patients develop solid tumors.
• As for the progression of the disease, many patients may later on progress to scleroderma or lupus.
• The most common cause of death from MCTD is from nephritis, a form of kidney disease.

Contributors:
Dr Christophe HSU – dermatologist. Geneva, Switzerland