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A few decades ago, scientists discovered that patients with a connective tissue disease had symptoms of both lupus, scleroderma, myositis, etc. These diseases are called ‘overlap-syndromes’. In 1969 Sharp and his co-workers found out that there is one specific type of overlap-syndrome with symptoms of lupus, scleroderma, myositis and rheumatoid arthritis, together with a large quantity of antibodies against one specific antigen, namely U1RNP. They believed it to be a distinct disease entity and called it MCTD.
Meanwhile, it is known that Sjogren’s Syndrome is very common in MCTD. It is still a matter of debate whether or not this disorder is diverse from the other overlap-syndromes. In general, however, this disorder is considered a distinct clinical entity.
Most important symptoms
Raynaud’s phenomenon
Is basically always present in the early phase of the disease, mostly without other symptoms at the level of the fingers, unless scleroderma is also present at the onset of the disease.
Swollen fingers
Mostly all the fingers are swollen in the overall length and become ‘sausage-like’. Sometimes this is only temporary, but occasionally it evolves into sclerodactyly (thin fingers with hard skin and limited mobility).
Arthritis
In the early phase there is painful swelling of the joints of the hands and feet like in rheumatoid arthritis. Damage to the cartilage or bone, however, is rare. As such, malformations do not occur or only seldom and the function of the joints remains intact. This kind of arthritis is comparable to the arthritis seen in lupus.
Muscle inflammation
In 10 to 20% of the cases, patients develop a real form of myositis, muscle inflammation (see polymyositis). Two out of three patients suffer from significant muscle pain (no weakening or paralysis), without demonstrable abnormalities in the laboratory test, electromyography or biopsy. Patients complain mostly of pain at the level of the large muscle groups of the shoulder girdle and the upper arms.
Lungs
The lungs may show the same abnormalities and problems as in scleroderma. Reduced lung volume is common, sometimes reduced absorption of oxygen and rarely overpressure in the lung vessels with fatal outcome occurs.
Oesophagus
The same complaints as in scleroderma may occur.
Heart
Inflammation of the heart sac or pericardium (pericarditis) may be acute. Unlike in polymyositis, inflammation of the heart muscle (myocarditis), which may cause heart failure or arrhythmia, occurs rarely. These complications are very serious and may be life threatening.
Neurological damage
Meningitis, psychological abnormalities due to brain damage, damage to the spinal marrow or facial nerves have been described. These symptoms occur often in Sjogren’s Syndrome, which often occurs in MCTD.
Renal involvement
Renal involvement is very rare and can be similar to the damage caused in scleroderma (especially damage to the renal blood vessels) as well as to the damage caused in lupus lupus (damage to the renal filtering units).
Skin and mucous membranes
The skin may show symptoms of scleroderma as well as of lupus. The mucous membranes (mouth, vagina) and the eyes may be dry due to the Sjogren’s Syndrome .
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