Undifferentiated Connective Tissue Disease (UCTD)

Undifferentiated connective tissue disease (UCTD) is an autoimmune disease. Autoimmune diseases are caused by your immune system attacking your body’s own healthy tissue.1

What is UCTD?

UCTD is a condition where someone has symptoms or signs of connective tissue diseases, but they do not meet the criteria for a diagnosis of a single disease. The main connective tissue diseases include:2

With UCTD, you may have symptoms from any one of these diseases or a combination of them.2

The word “undifferentiated” may make it seem like your doctor just does not know what to diagnose you with. This is not true. Even though UCTD can be difficult to diagnose, it is defined as its own disease.3

UCTD is similar to another disease that can cause combinations of symptoms, called mixed connective tissue disease (MTCD). However, MTCD is defined by a blood test result that shows a specific antibody called anti-U1-ribonucleoprotein (anti-U1-RNP) and requires specific features of multiple diseases.3

How is UCTD related to RA?

UCTD and RA are both autoimmune diseases. The symptoms of UCTD may also look very similar to RA symptoms. However, UCTD is not considered a common comorbidity or complication of RA. Doctors use the term comorbidity to describe a condition that occurs at the same time as another condition. Comorbid illnesses can interact in ways that make both worse.2

It is possible that UCTD may develop into a different connective tissue disease, like RA. However, this is unlikely. Scientists believe that fewer than 20 percent of people with UCTD eventually develop any definite connective tissue disease.4

Symptoms

UCTD can have many different symptoms. Symptoms can also change with time. The most common symptom is joint pain, which can be just as severe as RA joint pain. Other common symptoms include:4

  • Dry eyes or mouth
  • Numb or white hands and feet in the cold (sometimes called Raynaud’s phenomenon)
  • Rashes, typically on the face, upper arms, or chest
  • Low fevers

Some people with UCTD may develop low red or white blood cell counts. Most people with UCTD do not experience major organ damage. UCTD may be less likely to develop into a serious disease as compared to other connective tissue diseases.4

Diagnosis

UCTD can be difficult to diagnose because there is no one factor that identifies it. A UCTD diagnosis typically comes from ruling out other connective tissue diseases. This process will typically include a physical exam and blood tests.

Doctors may also use imaging tests or biopsies.2,4

In a blood test, doctors will look for antinuclear antibodies (ANA). ANA can be a sign of an autoimmune disorder, but they do not indicate which it may be. The blood test will also look for results that could show your symptoms are caused by a different disease. For example, people with RA may be positive for the antibodies anti-cyclic citrullinated peptides (anti-CCP) or rheumatoid factor (RF).2,4

If you have high ANA and autoimmune disorder symptoms but doctors still cannot diagnose you with another disease after these tests, they may diagnose you with UCTD. This process can be difficult, and researchers are studying better ways to diagnose UCTD.1

Treatment

UCTD is treated by managing the symptoms. There is no UCTD specific treatment. Doctors manage it by taking similar approaches to other autoimmune disorders. UCTD tends to be less severe than other autoimmune diseases, and treatment may not have to be as aggressive.4

Joint pain and inflammation can be treated with over-the-counter (OTC) anti-inflammatory pain relievers, like ibuprofen. Low doses of steroids can also help manage inflammation. Antimalarial drugs, which are often used to treat lupus, can also help ease symptoms.1

You may want to see a doctor every 6 months to make sure your UCTD is not worsening or developing into another condition. Worsening symptoms can be an indication that this may be happening. Your doctor can confirm it with tests.2,4

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Written by: Juliette Daly | Last reviewed: March 2021