Mixed connective
tissue disease is a term used by some experts to describe a collection
of symptoms similar to those of systemic lupus erythematosus, scleroderma,
polymyositis, and dermatomyositis.
About 80% of people who
have this disease are women. Mixed connective tissue disease affects
people from ages 5 to 80. Its cause is unknown, but it appears to
be an autoimmune disorder.
Symptoms
The typical symptoms are Raynaud's
phenomenon (in which the fingers suddenly become very pale and tingle
or become numb in response to cold or emotional upset (see Peripheral Arterial Disease: Raynaud's Disease and Raynaud's Phenomenon),
joint inflammation (arthritis), swollen hands, muscle weakness, difficulty
in swallowing, heartburn, and shortness of breath. Raynaud's phenomenon
may precede other symptoms by many years. Regardless of how mixed
connective tissue disease starts, it tends to worsen, and symptoms
spread to several parts of the body.
The hands are frequently
so swollen that the fingers look like sausages. A purplish butterfly-shaped
rash on the cheeks and bridge of the nose, red patches on the knuckles,
a violet discoloration of the eyelids, and red spider veins on the
face and hands all may appear. Skin changes similar to those in
scleroderma also may occur. The hair may thin.
Almost everyone with mixed
connective tissue disease has aching joints; about 75% develop the
swelling and pain typical of joint inflammation (arthritis). Mixed
connective tissue disease damages the muscle fibers, so the muscles
may feel weak and sore, especially in the shoulders and hips.
Although the esophagus
is often affected, it seldom causes difficulty in swallowing and
is not painful. Fluid may collect in or around the lungs. In some
people, abnormal lung function is the most serious problem, causing
shortness of breath during exertion.
Occasionally, the heart
is weakened, leading to heart failure (see Heart Failure).
Symptoms of heart failure may include fluid retention, shortness
of breath, and fatigue. The kidneys and nerves are affected in only
10% of people, and the damage is usually mild compared to the damage caused
by lupus. Other symptoms may include a fever, swollen lymph nodes,
abdominal pain, and persistent hoarseness. Sjögren's syndrome may
develop. Over time, most people develop symptoms that are more typical
of lupus or scleroderma.
Diagnosis and
Treatment
Doctors suspect mixed
connective tissue disease when some symptoms from lupus, scleroderma,
polymyositis, or rheumatoid arthritis overlap.
Blood tests are performed
to detect an antibody to ribonucleoprotein,
which is present in almost all people who have mixed connective tissue
disease. A high level of this antibody without the other antibodies
present in lupus is reasonably specific for mixed connective tissue
disease.
The treatment is similar
to that of lupus. Corticosteroids
are usually effective, especially when the disease is diagnosed
early. Mild cases can be treated with aspirin or other nonsteroidal
anti-inflammatory drugs (NSAIDs), quinacrine or similar drugs, or
very low doses of corticosteroids. The more severe the disease,
the higher the dose of corticosteroid needed. In severe cases, immunosuppressive
drugs may also be needed.
In general, the more advanced
the disease and the greater the organ damage, the less effective
the treatment. Scleroderma-like damage to the skin and esophagus
is least likely to respond to treatment. Symptom-free periods can
last for many years with little or no continuing treatment with
a corticosteroid. Despite treatment, mixed connective tissue disease
progresses in about 13% of the people, producing potentially fatal
complications in 6 to 12 years.
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