The typical symptoms are Raynaud's syndrome (in which the fingers suddenly become very pale and tingle or become numb or blue in response to cold or emotional upset—see Peripheral Arterial Disease: Raynaud's Syndrome), joint inflammation (arthritis), swollen hands, muscle weakness, difficulty in swallowing, heartburn, and shortness of breath. Raynaud's syndrome 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 systemic sclerosis 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. Tasks such as lifting the arms above the shoulders, climbing stairs, and getting out of a chair can become very difficult.
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 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 systemic sclerosis.
The first signs of chronic venous insufficiency are ankle and leg swelling. Swelling occurs because the blood that has pooled in the veins causes abnormally high pressure in the veins. As the pressure and swelling increases, the skin of the legs may actually leak tiny drops of plasma, which is the pale yellow fluid part of blood. Eventually, the capillaries burst under the high pressure, releasing red blood cells and giving that area of the skin a reddish-brown discoloration. The discolored skin is easily broken by a scratch or bump. When this happens, the patient frequently develops leg ulcers, called venous stasis ulcers, which can become infected. An infected skin ulcer will ooze pus and have a foul-smelling discharge. If the infection spreads to the surrounding tissue, the patient develops a condition called cellulitis. Other symptoms of chronic venous insufficiency include legs that ache, feel heavy, or feel tired, especially after long periods of standing; new varicose veins; leg skin that looks and feels leathery; and flaking and itching in the affected area of the legs
Prognosis: Despite treatment, mixed connective tissue disease worsens in about 13% of the people, causing potentially fatal complications in 6 to 12 years. The prognosis is worse for people who have mainly features of systemic sclerosis or polymyositis. Overall, 80% of people survive at least 10 years after the diagnosis is made. Symptom-free periods can last for many years with little or no continuing treatment with a corticosteroid.