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Connective tissue is a kind of cellular glue — a material found outside your cells that supports and gives form to tissues and organs throughout your body. Specialized forms of connective tissue occur in your skin, bones, ligaments and tendons.

Because it's so pervasive and varied, connective tissue can give rise to hundreds of complex and puzzling disorders. One of these is CREST syndrome, which usually affects your skin and blood vessels and in severe cases, your lungs, digestive tract or heart.

For some people, the problems are minor and don't interfere with normal functioning. But for others, CREST can be life-altering and even fatal. Because the disease has no known cure, treatments focus on managing symptoms and preventing serious complications.

CREST syndrome is a subset of scleroderma, a disorder that leads to thickening, hardening and tightening of your skin and connective tissue. In localized scleroderma the damage is confined to your skin and the tissue just beneath it, but systemic scleroderma is more far-reaching, affecting blood vessels and internal organs as well.

Systemic scleroderma is broadly divided into two types:

• Diffuse scleroderma. This form of the disease is marked by thickening of the skin of the extremities and trunk, by potentially serious damage to the esophagus, intestine, lungs, heart and kidneys, and by the late onset of the vascular condition called Raynaud's phenomenon.
• Limited scleroderma. This form usually affects skin only on the fingers, toes, throat and face and progresses much more slowly than the diffuse type does. Raynaud's phenomenon is often the first symptom of limited scleroderma, often occurring as much as 10 years before other signs and symptoms appear. Although CREST can occur in people with diffuse scleroderma, it's most often associated with the limited form of the disease — so much so that the terms are sometimes used interchangeably.

The signs and symptoms of CREST
CREST has a distinct set of characteristics that give the syndrome its acronymic name. These characteristics include:

• Calcinosis. In this condition, tiny calcium deposits develop under your skin, mainly on your elbows, knees and fingers, although they can occur almost anywhere, including your legs and spine. You can see and feel these deposits, which sometimes may be tender, drain a chalky fluid or become infected.
• Raynaud's phenomenon. For many people with CREST, Raynaud's phenomenon, which causes numbness, pain and color changes in your fingers, is the first indication of the disease. Often appearing years before other CREST symptoms, Raynaud's occurs when small blood vessels (capillaries) spasm in response to cold or emotional stress, blocking the flow of blood. Although not everyone with Raynaud's experiences the same symptoms during an attack, the areas of affected skin generally turn white before becoming blue, cold and numb. When circulation improves, the skin usually reddens and may throb or tingle. The various changes begin at your fingertips and move toward your wrists, with a clear line of demarcation between normal and affected tissue. Attacks of Raynaud's may last from a few minutes to several hours and tend to become worse over time. In severe cases, lack of circulation can lead to sores or ulcers on your fingers. Although almost everyone with CREST has Raynaud's, not everyone with Raynaud's has CREST. In fact, most people with Raynaud's have no underlying disease or associated medical problems.
• Esophageal dysfunction. People with CREST commonly experience problems with their esophagus — the tube that connects the mouth and stomach. Poor functioning of the muscles in the upper and lower esophagus can make swallowing difficult and cause stomach acids to back up into the tube, leading to heartburn, inflammation and scarring of esophageal tissues.
• Sclerodactyly. Thick, hardened skin (sclerodactyly) is the hallmark of scleroderma. In the diffuse form of the disease, skin thickening usually develops quickly and affects much of the body, including your hands, face, upper arms, upper legs, chest, and stomach. In people with CREST, however, skin changes usually occur gradually and affect only the fingers, toes, and sometimes the face and throat. At first the affected areas simply look puffy, especially in the morning, but over time the skin thickens and turns shiny as it stretches tightly over the underlying bone. Eventually, you may find that hardened skin makes it difficult to bend or straighten your fingers. Tightening of your facial skin sometimes can make speaking more difficult, but more often, the changes are cosmetic — tight skin can make your mouth smaller and narrower and thin your upper lip. Although these changes can't be prevented, plastic surgery may provide improvement.
• Telangiectasia. This is a collection of dilated blood vessels on the surface of your skin, usually so closely packed that they appear as solid red marks rather than as individual vessels. Although telangiectasia can develop almost anywhere, people with CREST syndrome are most likely to have them on the face, hands, lips and lining of the intestinal tract.

You don't have to have all these signs and symptoms to be diagnosed with CREST. Some doctors believe only two of the five are necessary for a diagnosis. This means that many variations on the general CREST theme can exist — for example:

• CRST, which means you have all the signs and symptoms of CREST except esophageal problems
• REST, which is CREST without calcinosis

Some people also have what's known as "overlap disease," in which CREST occurs in conjunction with scleroderma or other autoimmune conditions.

Connective tissue is an extensive and complex structural scaffold that surrounds and supports cells. It acts as a kind of mesh that holds your body together, rather like the wire framework on a screen, with your cells acting as the screen's holes. This highly tensile tissue, which is found in your skin, bones, ligaments and tendons, is made up of two major proteins, collagen and elastin. Collagen is particularly important: It's the most abundant protein in your body and the main component of ligaments and tendons. It also helps make your skin elastic and resilient.

In people with CREST syndrome, the immune system appears to stimulate cells called fibroblasts to produce excess amounts of collagen. Normally, fibroblasts synthesize collagen to help heal wounds, but in this case, the protein is produced even when it's not needed, forming thick bands of connective tissue around the cells of your skin, blood vessels and in some cases, your internal organs.

Although an abnormal immune system response and the resulting production of excess collagen appears to be the main cause of CREST syndrome, researchers suspect that other factors may play a role, including:

• Genetic makeup. Having a defect in the gene that codes for the protein fibrillin-1 or having other factors that make fibrillin-1 less stable may make you more susceptible to scleroderma. Because it's likely that other genes are involved in the disorder, research into the genetic component of scleroderma is ongoing.
• Pregnancy. Normally, a predisposition to certain diseases is passed from parent to child. But in an ironic genetic twist, women who have been pregnant may be more prone to CREST because of cells they receive from their fetus. These cells, which pass from a baby to its mother through the placenta, can linger in the mother's body for years after a child's birth. Because the mother's immune system perceives the cells as foreign substances, it may initiate a response in which immune cells attack healthy tissue. Exactly how and even if this process occurs isn't known, but researchers are continuing to study the potential link between fetal cells and scleroderma.
• Hormones. Women are far more likely to develop CREST than men are, especially during the childbearing years. Scientists suspect that the female hormone estrogen may be involved in the disease but haven't yet established a clear link.
• Environmental factors. Exposure to viral infections and some environmental toxins may trigger scleroderma in people who are genetically predisposed to develop the disease.

Because it's not entirely clear just what causes CREST, all the risk factors for the disease may not yet be known. Researchers do know, however, that women, and black women in particular, are far more likely to develop the disease than men are. This gender disparity may be linked to the effects of estrogen and to fetal cells acquired during pregnancy.

Other factors that may make you more susceptible to CREST include:

• Age. Most people who develop CREST are between 30 and 50 years old.
• Race. For reasons that aren't clear, Choctaw American Indians and people of Japanese descent have the highest rates of CREST. Among Choctaws, the incidence of the disease is 20 times as high as it is in the general population.
• Genetic factors. If someone in your family has an autoimmune disease — that is, a disease in which the immune system turns against the body's own tissues — you have an increased risk of developing CREST.
• Exposure to toxins. Toxic substances such as polyvinyl chloride, benzene and trichloroethylene may trigger scleroderma in people with a genetic predisposition to the disease. Scleroderma is also common among people who work in or live near gold mines.

See your doctor if you're experiencing any of the early signs of CREST — numbness, pain or color changes in your fingers, or gradual thickening or tightening of your skin. It's important to establish a diagnosis before the disease progresses and to determine if the condition has affected your internal organs.

Like other rare and complex disorders, CREST can be difficult to diagnose. Signs and symptoms vary widely and often resemble those of other connective tissue and autoimmune diseases. Further complicating matters is that CREST sometimes occurs with other conditions, leading to entirely new syndromes.

As if that weren't confusing enough, CREST can often look like undifferentiated connective tissue disease, a catch-all disorder for people who have signs and symptoms of several related connective tissue diseases but who don't fall into any clear diagnostic category. It may take years to reach a diagnosis in such cases.

Getting to a diagnosis
To help diagnose CREST, your doctor will take a complete medical history and perform a physical exam, looking especially for changes in the texture, color and appearance of your skin. Sometimes doctors take a small sample of skin (biopsy) that's then examined under a microscope in a laboratory. But although biopsies can be helpful, they can't definitively diagnose CREST or even distinguish between localized and systemic scleroderma.

You may also have laboratory tests to look for antibodies that are frequently found in the blood of people with scleroderma, especially the anticentromere antibody, which occurs in most people with CREST. Yet even this isn't definitive because not everyone with CREST has the antibodies.

CREST can be an elusive and frustrating disorder — one whose full range of defining symptoms may take years to appear. For some people, the diagnostic process may be the most difficult aspect of the disease.

In addition to tests that may help diagnose CREST itself, your doctor may recommend additional tests to identify any lung, heart or gastrointestinal complications.

The visible signs of CREST — tight, thick skin on your fingers, hands and face — can affect the way you feel about your appearance, make everyday tasks such as opening a jar or shaving more difficult, and even affect your speech. But the most serious complications tend to occur beneath your skin. Some of those complications include:

• Gastrointestinal problems. Although CREST can affect tissue anywhere along your digestive tract, damage to your esophagus is the most common gastrointestinal complication. Changes in the functioning of esophageal muscles can cause difficulty swallowing and chronic heartburn, which in turn can lead to Barrett's esophagus, a serious pre-malignant condition, and to an increased risk of esophageal cancer.

  When CREST affects your intestine, you may develop constipation or diarrhea, bloating after meals, and gas. More severe tissue damage can affect your ability to absorb nutrients from your food, leading to weight loss and malnutrition.

• Lung damage. Excess collagen can cause scarring of the tissue between the air sacs in your lungs. This condition, known as pulmonary fibrosis, interferes with the transfer of oxygen from your lungs to your bloodstream, leading to breathing problems and a reduced capacity for exercise. CREST can also cause high blood pressure in the arteries in your lungs (pulmonary hypertension), a progressive and potentially fatal condition.
• Heart problems. Scarring of heart tissue can lead to abnormal heart rhythms (arrhythmias) and in rare cases to an inflamed heart muscle (myocarditis).
• Arthritis and arthralgia. Although arthritis is far less likely to occur with CREST syndrome than it is with diffuse scleroderma, many people with CREST experience joint pain (arthralgia) without having the inflammation that characterizes arthritis.
• Dental problems. Severe tightening of facial skin can cause your mouth to become smaller and narrower (microsomia), putting you at risk of serious dental problems. A measurably smaller mouth makes it hard to brush your teeth or have them professionally cleaned, upping the chances of tooth decay. And because people with CREST often don't produce normal amounts of saliva, the risk of decay increases even more. In addition, acid reflux can destroy tooth enamel, and changes in gum tissue may cause your teeth to become loose or even fall out.
• Sicca syndrome. Affecting about a third of people with CREST, sicca syndrome causes dry eyes, a dry mouth and sometimes dry airways.

CREST has no known cure, but the signs and symptoms of the disease can often be effectively managed using both medical and nonmedical therapies. Success rates vary from person to person.

Treatments for the various aspects of CREST include:

• Calcinosis. Doctors have tried a number of drugs to treat calcium deposits with little success, although the antibiotic minocycline can sometimes reduce inflammation and ulcers in severe calcinosis. Very large or painful calcium deposits are sometimes surgically removed. A few doctors report that treatment with a carbon dioxide laser may be effective at relieving symptoms and preventing deposits from returning.
• Raynaud's phenomenon. Although drug and even surgical options exist for treating Raynaud's, self-care measures are often highly successful and are usually tried first. These measures include keeping your body's core temperature elevated and protecting your hands and feet from cold, both indoors and out. Biofeedback, a technique that teaches you to control certain body responses; autogenics training, a type of progressive muscle relaxation; and hypnosis all can help improve blood flow to the extremities. If these methods fail, your doctor may prescribe a vasodilator such as a long-acting calcium channel blocker, a drug that can open small blood vessels and increase circulation. Side effects, especially in the short-acting versions of the drug, include swelling, headache, dizziness and increased acid reflux. Other treatments for Raynaud's include topical nitroglycerin, which can help heal skin ulcers.
• Esophageal dysfunction. Certain lifestyle changes can help reduce problems with swallowing and especially with acid reflux. These measures include eating small meals that emphasize soft-textured foods; waiting three to four hours after a meal before lying down; and avoiding alcohol, caffeine, chocolate and spicy foods, which can aggravate heartburn. Your doctor may also suggest an H-2 blocker such as Pepcid, Tagamet or Zantac to help relieve pain and burning by reducing the production of stomach acid.
• Sclerodactyly. In the past, treatments for tight, thick skin were largely superficial — moisturizers for dryness and cortisone creams for inflammation. But light therapy (phototherapy) may prove more therapeutic. Using ultraviolet A (UVA) radiation for skin problems isn't new — it has long been a mainstay of psoriasis treatment, but it now appears that long-wave UVA-1 radiation may also reduce the proliferation of collagen in people with localized scleroderma. UVA-1 therapy is expensive, available on a limited basis and may not be an option for people with minor skin changes. For many people with CREST, an altered appearance may be the most challenging aspect of the disease. Although not every change can be corrected, plastic surgery may offer improvement in some cases.
• Telangiectasia. Dilated capillaries can be hidden with makeup or reduced or eliminated with laser therapy.

CREST can be profoundly frustrating — it's difficult to diagnose, has no known cure, and its wide-ranging signs and symptoms tend to become progressively worse. Still, your own efforts can play a key role in managing your symptoms, preventing complications and making the disease easier to live with.

• Stay active. Regular exercise helps control your weight, reduces the risk of dozens of serious diseases including heart attack, stroke, diabetes and some cancers, relieves depression, and even helps reduce chronic pain. It also can boost the circulation in your hands and feet and reduce stress — crucial factors in managing Raynaud's phenomenon.If you have lung complications that affect your breathing, exercise is still important, although your doctor may recommend less strenuous activities such as walking or swimming. And if you have trouble with range of motion in your fingers, a physical or occupational therapist can suggest new ways to perform everyday activities or recommend assistive devices to make tasks more manageable.
• Don't smoke. If you smoke, talk to your doctor about the best ways to quit. Nicotine constricts your blood vessels, making Raynaud's phenomenon worse. What's more, smoking can cause permanent narrowing of your blood vessels over time.
• Protect yourself from cold. Good circulation is essential for preventing the discomfort and complications of Raynaud's phenomenon. Although medications can help keep blood vessels open, you can take steps that may be equally if not more effective. First, protect your hands and feet from cold temperatures. Wear gloves outdoors when the weather is cool and indoors when you reach into the freezer or have your hands in cold water. But warm hands aren't enough — to keep blood vessels open, you also need to maintain your body's core temperature. In chilly weather, dress in layers and wear a hat or scarf, thermal socks, and well-fitting boots or shoes that don't cut off your circulation. Finally, consider biofeedback, relaxation exercises or hypnosis to help improve blood flow.
• Take care of your digestive tract. Because CREST can affect any part of your digestive system, you may experience problems ranging from heartburn to diarrhea and malnutrition. You can help minimize acid reflux by eating small, frequent meals, by avoiding spicy or fatty foods, chocolate, caffeine and alcohol, by not exercising immediately before or after eating, and by sitting upright for two or three hours after a meal. If you have difficulty swallowing, choose soft, moist foods and chew them well. Your doctor may recommend fiber supplements for constipation, antibiotics or over-the-counter remedies for diarrhea, and dietary supplements for malabsorption.
• Find ways to manage stress. Stress contributes to a host of diseases, but it's particularly detrimental for people with Raynaud's because of its affect on circulation. And although stress-reduction advice is everywhere these days, finding truly effective ways to deal with stress is challenging, especially when you're living with a chronic illness. No one approach or technique is right for every person, but many people have been helped by meditation, deep breathing, guided imagery or other relaxation techniques, by massage or by regular exercise. On the other hand, extraordinary measures aren't always necessary: Family ties, friendships and involvement in social activities also can offer a psychological buffer against stress and help you cope better with illness.
• Keep your skin moist. Excess collagen destroys sweat and oil glands, leaving your skin stiff and dry. To help soften your skin, keep it as moist as possible. Bathe just once a day or every other day, and limit baths and showers to 15 minutes or less, using warm rather than hot water. Less is more when it comes to washing your face, too. Although it may be difficult to break the habit of cleansing your face morning and evening, once a day should be enough to remove dirt and oil. Whenever you bathe, avoid harsh soaps and detergents. Instead choose cleansing creams or gentle skin cleansers and bath or shower gels with added moisturizers. Apply a rich oil-based moisturizer immediately after washing your hands or bathing, while your skin is still damp. It's important to moisturize your house, too, using a humidifier to maintain moisture levels at 40 percent to 50 percent.
• Practice good oral hygiene. If you have trouble brushing and flossing your teeth because of stiffness in your fingers and hands, ask your dentist or an occupational therapist about special toothbrushes and flossing devices. An occupational therapist can also recommend exercises that help keep your mouth more flexible. Be sure to have regular checkups and use any special rinses or toothpastes your dentist recommends. If your mouth is chronically dry, try drinking more water and sucking on ice chips or hard, sugarless candy. When these measures fail, your dentist may prescribe a medication to stimulate the flow of saliva.