Can UCTD and MCTD occur together?

Q. I am ANA positive with limb and muscle weakness. Is this UCTD or MCTD?

Answered by
Dr. Naval Mendiratta
and medically reviewed by iCliniq medical review team.
This is a premium question & answer published on Dec 27, 2019 and last reviewed on: Jul 14, 2023

Hello doctor,

I am currently struggling with a flare that is just not getting better. My symptoms started three years ago. At that time my ANA was high positive, lupus anticoagulant positive, but nothing else specific. My symptoms are joint pain, swelling, severe fatigue, severe hand swelling, severe Raynauds, GERD, nausea, constipation, dysphagia, eye swelling, occasional strange rashes from the sun, and muscle weakness. My ANA is high positive and speckled. RNP, chromatin ab, and RNP (but anti-smith is negative?) are positive. Scleroderma, anti-DNA, and Sjogren's ab's negative. I also have Hashimotos but the thyroid is functioning fine I was recently put on Prednisone 10 mg daily. My doctor is not increasing the dose because of psychological side effects. I have an eye exam to start with Plaquenil this week. My joint pain and GI symptoms are now under control. I am now struggling with limb weakness, muscle burning (like I am lifting weights). I am unable to work and live completely independently because of it. When my doctor assessed muscle strength she said it was abnormal (4/5 against resistance, lots of muscle shaking). My ESR and CPK were normal but I was not experiencing muscle issues at the time blood was drawn. I am getting more labs done and will possibly be referred to a neurologist at my next visit in a few weeks. My question is, based on the positive labs and symptoms, what diagnosis is likely? She has said both UCTD and MCTD, not lupus because of the symptoms. What is your general opinion? And out of curiosity, what is the difference between RNP/sm and sm ab? My current medications are Prednisone 10 mg QD, Cymbalta 60 mg QD, Flexeril 10 mg QHS, and Naproxen BID.



Welcome to

I believe your diagnosis is Overlap syndrome, scleroderma with myositis overlap. Your symptoms do not fit into one connective tissue disease. It is probably overlap of two diseases going on. Lupus I will not be too sure, as you do not specify symptoms pertaining to it. Neither it is UCTD (undifferentiated connective tissue disease). MCTD (mixed connective tissue disease) is more of a diagnosis of antibody only if U1 RNP (ribonucleoprotein) is positive. But in either ways management does not change much. But the antibodies you have to go more in favor of myositis with scleroderma overlap. For management point of view, you would need to increase the steroids dose. 10 mg is not gonna take care of the muscle disease. Plus you need a steroid sparing drug like Azathioprine or Methotrexate along with Plaquenil. ESR (erythrocyte sedimentation rate) and CRP (C-reactive protein) can be normal in scleroderma. So it is not much a criteria to follow up. Key is your muscle weakness, which needs to be taken care of before it keeps getting damaged. Sorry to say, but your doctors are taking it a bit slowly as at this stage aggression is needed. Psychiatry side effects will not come at a lower dose. I would recommend 30 mg at least to begin with and then start a tapering schedule. I hope CPK (creatinine phosphokinase test) and LDH (lactic acid dehydrogenase) levels have been checked as well. Lastly, make sure that a 2D echo to look for pulmonary artery pressure and HRCT (high resolution computed tomography) of the lungs to look for any lung involvement has been carried out.

I hope this helps.

The Probable causes:

Scleroderma with myositis overlap.

Investigations to be done:

CPK, LDH, 2D echo, and HRCT thorax.

Preventive measures:

Avoid cold exposure.

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