Maybe it’s the word “undifferentiated” that makes undifferentiated connective tissue disease (UCTD) seem a little vague. But it is a real medical condition. The Hospital for Special Surgery defines UCTD as a “condition in people who have symptoms and lab test results that indicate a systemic autoimmune disorder or connective tissue disease, but which do not meet enough such characteristics to indicate a diagnosis for a well-defined connective tissue disease.”
“UCTD isn’t as clear-cut a diagnosis in the sense that lupus or rheumatoid arthritis can be in many cases,” says Michael D. Lockshin, MD, director of Barbara Volcker Center for Women and Rheumatic Diseases, at Hospital for Special Surgery in New York City.
Instead, adds Dr. Lockshin, UCTD is part of a spectrum of autoimmune rheumatic diseases (also known as connective tissue diseases) and you can have symptoms of any one of the five classic ones.
The 5 Main Connective Tissue Diseases
What they all share is that your immune system mistakenly attacks the tissues in your body that are responsible for holding the cells together. These five diseases include:
Lupus, or systemic lupus erythematosus (SLE): an inflammatory disease that can attack multiple organs like your kidneys, your joints, and skin. Common lupus symptoms include rashes and joint pain.
Rheumatoid arthritis (RA): a condition that can lead to long-term destruction of your joints and cause damage to organs such as your lungs and cardiovascular system. RA symptoms include joint swelling and pain.
Scleroderma: a rare disease that causes your body to overproduce collagen, causing your skin and connective tissues to thicken. One early sign of the disease is Raynaud’s syndrome, which makes your fingers extra sensitive to cold, change color, and swell.
Myositis: a condition that attacks the muscles closest to the trunk of your body (such as your thighs or shoulders) that leads to muscle weakness and fatigue. If you have dermatomyositis, you have rashes as well.
Sjögren’s syndrome: an inflammatory disease that mostly affects your saliva and tear glands, leading to dry eyes and mouth.
With UCTD, you could have rashes that flare up when you’re in the sun along with joint or muscle pain, for instance. These symptoms could lead a doctor to think you have lupus or dermatomyositis, but with UCTD, lab tests wouldn’t be able to confirm that diagnosis. Or the bloodwork may come back showing signs for several different conditions, so it’s challenging for a doctor to pinpoint the one(s) you actually have.
In short, doctors diagnose UCTD when your symptoms suggest you have some type of connective tissue disease but diagnostic tests can’t determine the specific one you have.
Who Gets Undifferentiated Connective Tissue Disease
Like many autoimmune disorders, UCTD patients are most often young women who get diagnosed between the ages of 15 and 35, says Terry Moore, MD, a rheumatologist and professor at the department of internal medicine, division of rheumatology, at Saint Louis University School of Medicine in St. Louis, Missouri. And like so many autoimmune conditions, no one is sure what really causes it either, though there are theories.
“Pretty much everyone who develops the illness starts with a genetic predisposition. That leaves them susceptible to a trigger,” says Dr. Lockshin. “It might be an infection, it might be an environmental agent, it might be something that we don’t know about yet. That trigger puts the person into a different pathway that develops the disease — and which [connective tissue] disease develops depends on what their genes are like and what their environment is.”
Symptoms of Undifferentiated Connective Tissue Disease
For many people with UCTD, the main signs are achy joints and arthritis in the elbows, wrists, hands, and knees in a symmetrical pattern, says Dr. Lockshin. People with UCTD generally don’t have as much swelling and the pain is transient. “Some days are good, other days aren’t so good,” he explains.
But just because the pain can come and go doesn’t mean it’s not debilitating. “Some of these people have really devastating disease that you can’t put a label on. Others describe it as sort of mild nuisance, and there’s everything in between,” Dr. Lockshin explains. “The arthritis pain can be just as bad as that in rheumatoid arthritis or lupus arthritis. It’s just that you can’t pin it down to a specific of one of those names.”
Rashes are another symptom. They generally don’t appear on the face, but more typically on the upper arms and chest. These rashes can be blotchy, scaly, and even sun sensitive, says Dr. Lockshin.
Other signs of undifferentiated connective tissue disease include:
- Dry eyes or dry mouth
- Raynaud’s phenomenon, when your hands and feet turn white and blue and feel numb when it’s cold
- Muscle weakness
- Hair loss
- Abnormal blood counts (either slightly lower than normal white blood cells, the cells used to fight infection, or low platelets, the cells that allow your blood to clot)
- Pleuritis or pericarditis, inflammation of the lining of the lungs, which can cause chest pains
You probably won’t have all these symptoms, though the symptoms are the first clue that doctors use, along with your medical history, to figure out if you have UCTD or some other autoimmune disease. Of course, the diagnostic tests have to bear these out.
Diagnosing Undifferentiated Connective Tissue Disease
Doctors are looking to see whether you could have one of the main connective tissue diseases before diagnosing UCTD. Your provider will give you a thorough work-up, including a physical exam, blood tests, and sometimes imaging tests and biopsies to home in on what may be causing your symptoms.
All autoimmune rheumatic diseases have a set of diagnostic criteria that are used to make a diagnosis, which includes evaluating a physical exam, medical history and blood tests, as well as imaging tests and biopsies in some cases.
Your doctor may diagnose UCTD if you have some symptoms and some lab test results that suggest you could have a connective tissue disease but you do not meet the full diagnostic criteria for lupus, rheumatoid arthritis, scleroderma, myositis, Sjögren’s syndrome, or others.
Physical exam and medical history
A rheumatologist will ask you about your symptoms. For example, you might be asked whether your joint pain or tenderness is worse in the morning or whether your rash gets worse in the sun. Then the doctor will check out any rashes, swollen joints, dry eyes, and other physical signs of your condition.
Doctors order blood tests to check for the presence of various proteins called antibodies, which are present when the body’s immune system is attacking itself. The types of antibodies you have depend on the type of autoimmune disease.
For UCTD in particular, doctors are looking for antinuclear antibody (ANA), which attacks your body’s tissues. Even though up to 15 percent of healthy people may test positive for ANAs, their presence is almost always a sign of an autoimmune disorder, such as lupus or Sjögren’s.
People with UCTD tend to have a positive ANA but not for other antibodies associated with other autoimmune conditions. If you have another connective tissue disease, you’ll also have more specific types of ANAs as well as other proteins. For example:
- People with lupus may also test positive for anti-double-stranded DNA antibody (anti-dsDNA) and anti-Smith (anti-Sm) antibody.
- People with myositis may have elevated levels of a muscle enzyme called creatine kinase (CK) that could be a sign of polymyositis.
- People with rheumatoid arthritis may test positive for the antibodies anti-cyclic citrullinated peptides (anti-CCP) and rheumatoid factor.
- People with Sjögren’s may test positive for anti-Ro (SS-A) and anti-La (SS-B) antibodies as well as rheumatoid factor
A rheumatologist might also order X-rays to see if there is joint damage, which is a hallmark of both rheumatoid arthritis and UCTD, though this is not as common in UCTD. You might also have a CT scan to look for lung damage.
If your bloodwork comes back positive for antibodies and markers for polymyositis or Sjögren’s disease, your provider will likely order a biopsy. Your provider will take samples of muscle tissue or from the saliva glands that line your lower lip to check for inflammation.
After the test results come back, you’ll be diagnosed with UCTD if you have a positive ANA and symptoms of an autoimmune disorder but don’t meet the specific criteria for the classic autoimmune rheumatic diseases, says Dr. Lockshin.
Is Undifferentiated Connective Tissue Disease an Early Stage of Something Else?
Whether or not UCTD will progress and ultimately become a different disease is a common question among newly diagnosed patients. There’s no easy answer.
When Spanish researchers followed 98 UCTD patients for a number of years, they found that 62 percent of patients continued with a UCTD diagnosis, 24 percent went into remission, and 14 percent eventually got diagnosed with another connective disease.
In Dr. Lockshin’s experience, about half of his UCTD patients have gone on to develop another autoimmune disorder, most commonly lupus, usually within a timeframe that can range from five to 20 years. “The other half either go into remission or just stay with UCTD for the rest of their lives,” he adds.
Which connective disease patients will go on to develop sometimes can be apparent with your symptoms. For example, if you have skin rashes or if your kidneys are affected, that might point to lupus. “If patients have more muscle abnormalities, then you’re going to think about polymyositis,” Dr. Moore explains. “If they have a lot of skin manifestations, with tight skin tightening or changes, you think about scleroderma.”
The UCTD diagnosis can have its drawbacks. “If the tests don’t come back positive, some doctors tend to say, ‘Oh it’s in your head,’ and dismiss patients,” says Dr. Lockshin. Getting insurance to cover tests and treatments is yet another issue, he adds.
And follow-up visits — to monitor symptoms and tests in order to see whether the UCTD has progressed — are key, but don’t always happen. European researchers found that UCTD patients felt their condition wasn’t taken as seriously as other autoimmune rheumatic disorders and follow-up with additional medical visits tended to be inconsistent, especially if patients’ symptoms were on the mild end.
Undifferentiated Connective Tissue Disease vs. Mixed Connective Tissue Disease
Although these conditions sound similar, they are different. People with UCTD have some symptoms of various connective diseases, like arthritis or muscle pain, and positive ANA antibodies. But they don’t meet the criteria to make an official diagnosis.
On the other hand, mixed connective tissue disease (MCTD) is a mixture or overlap of three different autoimmune rheumatic diseases: lupus, scleroderma, and myositis.
People with MCTD have symptoms and features of all three conditions, either at the same time or over a period of time. For example, they might have Raynaud’s, muscle aches, fatigue, and puffy fingers. Over time, they can develop swollen, arthritic joints and inflammation of the heart and lungs. Patients not only have positive ANAs, but another type of antibody called RNP (nuclear ribonucleoprotein), which about half of all lupus patients have also.
What Is the Difference Between UCTD and Early Inflammatory Arthritis?
If you have undifferentiated connective tissue disease, you probably have arthritis or at least achy joints. But you’re also likely to have one or more symptoms that involve your entire body, like fatigue, muscle weakness, or rashes.
“Early inflammatory arthritis basically means that the patient mainly has just arthritis,” Dr. Moore notes. “These patients have swollen joints and will usually have inflammatory markers like an elevated sedimentation rate or C-reactive protein. But they’ll be negative for rheumatoid factor and anti-CCP antibody, which are more specific for rheumatoid arthritis. And their ANA and all the other tests are negative, too.”
Many people with early inflammatory arthritis go on to develop rheumatoid arthritis or psoriatic arthritis, especially if their joints are swollen and painful, he explains.
Treatment for Undifferentiated Connective Tissue Disease
There’s no FDA-approved treatment for UCTD. Instead, doctors treat the symptoms. In general doctors try to avoid using corticosteroids like prednisone or disease-modifying anti-rheumatic drugs (DMARDs) for mild cases of UCTD. The two treatments doctors most commonly recommend for UCTD are:
Non-steroidal anti-inflammatory drugs (NSAIDs): These anti-inflammatory pain relievers, like ibuprofen, may be used to treat arthritis related to UCTD.
Hydroxychloroquine (Plaquenil): Somewhat infamous for being studied as a now-ineffective treatment for COVID-19, hydroxychloroquine is used to treat a variety of inflammatory autoimmune conditions, including lupus, for which it is considered a first-line therapy, and rheumatoid arthritis. It helps with pain and swelling, and it can help prevent joint damage. “It’s a very safe drug to use,” says Dr. Lockshin, which is why doctors prescribe it so often. The side effects include nausea and diarrhea, which sometimes get better after you’ve been taking the drug for a while.
You’ll want to see a rheumatologist every six months to make sure your UCTD isn’t developing into another connective tissue disease or getting worse, says Dr. Moore. Some signs that may be happening:
- Your rashes are getting blotchier or covering a wider area
- Your eyes and mouth are becoming drier
- You develop Raynaud’s syndrome
- Your joints are more painful and swollen
Your doctor will test your blood every six months too, checking to see if any inflammatory markers like C-reactive proteins are increasing or if you’ve developed more specific ANAs or other antibodies, another sign that your UCTD may be turning into another condition.
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