Making sense of mixed connective tissue disease

DEAR DR. ROACH: One rheumatologist diagnosed me with unspecified mixed connective tissue disease and Raynaud’s syndrome. I was put on Plaquenil, which caused some hair loss and thinning. I got a second opinion from another rheumatologist, who said that based on my bloodwork, I do not have Raynaud’s or mixed connective tissue disease. Is it possible that mixed connective tissue disease goes into remission? Should I get a third opinion?

ANSWER: Many people probably are unfamiliar with the term “mixed connective tissue disease.” Other connective tissue diseases are well-known: Systemic lupus erythematosus (“lupus”), systemic sclerosis (“scleroderma”) and rheumatoid arthritis are common. Dermatomyositis and polymyositis are less well-known but are distinct inflammatory muscle diseases. In mixed connective tissue disease, there are elements of lupus, scleroderma and polymyositis, but these often occur at different times in the course of the disease.

The diagnosis of MCTD is made by a combination of blood tests and what we call “clinical criteria,” made up of symptoms (what people notice) and signs (what a clinician finds on an exam). The blood test is for what are called anti-RNP antibodies. These antibodies need to be present at high levels in order to make the diagnosis. However, the blood test alone does not make the diagnosis; some of the following — swelling in the hands or joints, muscle pain or inflammation, and Raynaud phenomenon (dramatic change in blood flow to the hands in cold weather, often accompanied by colour changes) — also need to be present to make the diagnosis of MCTD.

So, unfortunately, I don’t have enough information to say whether you have MCTD. If the first blood test showed high anti-RNP and you have had the symptoms of Raynaud, you would still need to have at least two of the other symptoms (swollen fingers or joints and muscle inflammation) at some point. If the second test showed no antiRNP antibodies, then that would make the diagnosis of MCTD very unlikely, as these antibodies usually stay around.

Raynaud phenomenon (it’s called “Raynaud’s syndrome” if it occurs by itself, not as part of MCTD or another condition) is a clinical diagnosis. It doesn’t depend on blood tests.

Symptoms in people with mixed connective tissue disease, just as in people with lupus, sometimes come and go for no discernable reason. I wouldn’t say that it’s in remission so much as that it is just not active. It’s possible that the hydroxychloroquine (Plaquenil) helped with the symptoms, but it’s also possible that they just went away on their own, even if you do have MCTD.