Undifferentiated Connective Tissue Disease (UCTD)

Undifferentiated connective tissue disease (UCTD) and mixed connective tissue disease (MCTD) are conditions that have some similarities to other systemic autoimmune or connective tissue diseases, but there are distinctions that make them different. When the criteria for named autoimmune diseases are not met, the condition is defined as UCTD.

There are 5 named autoimmune connective tissue diseases. They are classified based on a combination of symptoms, physical exam findings, and antibody testing.

They are:

• Rheumatoid arthritis
• Sjögren's disease
• Systemic lupus erythematosus
• Scleroderma
• Inflammatory myopathy

If you meet the classification criteria for more than one autoimmune connective tissue disease, this is described as overlap syndrome. MCTD is a specific overlap syndrome with features of systemic lupus erythematosus, scleroderma, and inflammatory myopathy with antibodies to RNP.

Features of Undifferentiated Connective Tissue Disease

If you have UCTD, you can have symptoms like joint pain, lab test results such as a positive ANA, or other features of systemic autoimmune disease.

Characteristic symptoms of UCTD include arthritis, arthralgia, Raynaud's phenomenon, leukopenia (low white blood cell count), rashes, alopecia, oral ulcers, dry eyes, dry mouth, low-grade fever, and photosensitivity. Typically, there is no neurological or kidney involvement, and the liver, lungs, and brain are generally not involved. About 80% of people with this condition have antibody testing that's positive for anti-Ro or anti-RNP autoantibodies.

Approximately one-third of those who are diagnosed with UCTD go into remission, and about one-third maintain a mild course of UCTD. It is thought that 30% of those who are initially diagnosed with UCTD progress to a definitive diagnosis of a defined connective tissue disease.

Diagnosing and Treating UCTD

As part of the diagnostic process for UCTD, a complete medical history, physical examination, and laboratory testing is necessary to exclude the possibility of other rheumatic diseases. The treatment is typically focused on managing the symptoms.

Usually, treatment for UCTD consists of some combination of analgesics and non-steroidal anti-inflammatories (NSAIDs) to treat pain and topical corticosteroids for managing the effects on the skin and mucous tissue. Sometimes Plaquenil (hydroxychloroquine) a disease-modifying anti-rheumatic drug (DMARD) is used. If improvement is insufficient, low dose oral prednisone may be added for a short time frame.

Methotrexate may be an option for hard-to-treat cases of UCTD. High doses of corticosteroids, cytotoxic drugs (e.g., Cytoxan), or other DMARDs (such as Imuran) are generally not used.

The Bottom Line 

The prognosis for UCTD is surprisingly good. There is a low risk of progression to a well-defined connective tissue disease, especially among patients who experience unchanged UCTD for 5 years or more.

Most cases remain mild, and symptoms are usually treated without the need for heavy-duty immunosuppressants.