Idiopathic Inflammatory Myopathies


A brief review of idiopathic inflammatory myopathies, ranging from pathology to the goals of treatment.


W. Hayes Wilson, MD: Our second topic is idiopathic inflammatory myopathies: dermatomyositis, polymyositis. I’m going to ask you the same questions there. I’ll start with the easy one first. What causes it?

Kostas N. Botsoglou, MD: What causes it again, dysregulation of the immune system resulting in aberrant inflammation, primarily presenting as proximal muscle weakness. There can be a classical rash with dermatomyositis as well as other organ involvement, including the lung and heart. It’s a rare disease, even more rare than lupus, and we typically can diagnose it with serologies and laboratory work including CPKs [creatine phosphokinase levels] and a muscle biopsy.

W. Hayes Wilson, MD: You’ve already mentioned proximal muscle weakness, which is typical in inflammatory myopathies, and skin rash of dermatomyositis. In the diagnostic work-up, where do you start when you suspect somebody might have an idiopathic inflammatory myopathy? What are some of the first steps you take?

Kostas N. Botsoglou, MD: I am always checking inflammatory markers in all our patients. In this population, CPKs and aldolase can be helpful. We have the option to also check a myositis panel. Our local lab here has 12 serologies, including the Jo antibody and some of the more esoteric antibodies that can be drawn and can help guide our diagnosis. Occasionally, if the suspicion is there but the lab isn’t remarkable, we will order an MRI of the quadriceps, and otherwise muscle biopsy is the standard.

W. Hayes Wilson, MD: The proof of the pudding is in the tasting, so getting a piece of muscle, but sometimes that’s difficult. Also timing, if you want to go ahead and treat the patient but you want to get a good biopsy and we must do it before they get too much prednisone. What are some of the things you think about in your differential diagnosis when you’re talking about idiopathic inflammatory myopathies?

Kostas N. Botsoglou, MD:We cannot forget malignancies, they can always mask as some of our conditions, especially if they are not responsive to treatment. Hypothyroidism is another condition and just more neuromuscular diseases like perhaps MS [multiple sclerosis] or Guillain-Barre syndrome, along those lines.

W. Hayes Wilson, MD: EMG [electromyography] and nerve conduction velocities are important, and it’s important also to remember that you want to do them just on one side. If you’re going to do the biopsy, do it on the other side, you don’t want to biopsy where you stuck needles in. And as you mentioned T1/T2 images, STIR [short inversion time inversion recovery] images on MRI can be helpful. I remember when I first started my career, I was at Emory University, it had an MRI and they built the whole building around it, and they used to call things on the MRI, UBOs—unidentified bright objects. We are little better with that now. But the MRI can help guide the biopsy as well. That’s good. I guess you might agree that our goals for therapy are very similar, trying to minimize the morbidities of the disease and improve the health outcomes. Would you agree?

Kostas N. Botsoglou, MD: Absolutely.

W. Hayes Wilson, MD: I want to thank all those out there who are watching this HCPLive® Peers and Perspectives. If you enjoyed the content, please subscribe to our e-newsletters to receive upcoming programs and other great content right in your inbox.

Transcript edited for clarity.

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