Undifferentiated connective tissue disease (UCTD)

This is a name of disease for patients who have  signs and symptoms of  rheumatic diseases, but not enough symptoms of one disease to make a definitive diagnosis. In other words, their condition is not “differentiated” into a particular connective tissue disease.

Over time, UCTD can follow three scenarios: it can change into a systemic disease, for example  systemic sclerosis, systemic lupus erythematosus, or rheumatoid arthritis; it can remain undifferentiated; or it can improve spontaneously.

Overlap syndromes

This is a disease combination in which patients have symptoms and laboratory abnormalities characteristic of two or more connective tissue diseases.

Mixed connective tissue disease (MCTD)

This disease is characterized by the symptoms of one or few connective tissue diseases and positive test for the anti-RNP antibodies (blood test).