When symptoms of Mixed Connective Tissue Disease first appear, they may suggest that the person affected has any one of several rheumatic diseases. However, when a person has mixed connective tissue disorder, the symptoms aren't as severe or as widespread as they would be if the person has lupus, scleroderma, rheumatoid arthritis or other rheumatic disorder.
This condition has many symptoms, including:
- Pain in two or more joints. Almost all persons with mixed connective tissue disease have this symptom. Three out of four persons with the condition have arthritis and may have the swollen, deformed joints of rheumatoid arthritis.
- Raynaud's phenomenon. This symptom may appear years before any other.
- Skin changes. These can be like those of lupus or red patches over the knuckles, violet discolorations of the eyelids, loss of hair over the body and abnormal opening up (dilation) of the capillaries of the hands and face that may form a tumor
- Swollen hands. This is the most common symptom. With time, the fingers look more and more like sausages.
- Muscle weakness. There may sometimes also be tenderness.
- Difficulty swallowing and keeping food in the stomach.
- Loss of sensation in the nerves of the face and head.
- Lung disorders. Nearly 80% of the people with mixed connective tissue disease have some involvement of the lungs. Symptoms can include inflammation of the lining that covers the lungs and the inside of the chest, difficulty breathing or pulmonary hypertension.
- Kidney disease. Only about one out of every 10 patients has this symptom, which is often mild. In some cases, however, it can become life threatening.
Causes and Risk Factors
It isn't yet known what causes this disease. In some cases, it gets worse and develops into scleroderma or lupus. Several factors, however, suggest that mixed connective tissue disease is a distinct disorder in its own right. These include symptoms shared by several rheumatic conditions, the presence of certain antibodies, abnormalities in the system that regulates the body's immune response and frequent pulmonary hypertension.