Dermatomyositis and Polymyositis (DM/PM)

Author: Shelley Ensz. Scleroderma is highly variable. See Types of Scleroderma. Read Disclaimer
Myopathy and Myositis
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Myopathy and Myositis

Dermatomyositis KaleidoscopeMyopathy vs. Myositis. Myopathy means muscle disease. Myositis means muscle disease that is caused by inflammation. There are three types of myositis: dermatomyositis, polymyositis, and inclusion body myositis. ISN.

Myopathy vs. Myositis
Myopathies and Scleroderma
Myopathies and Overlapping Diseases

What is Dermatomyositis?

Inflammatory muscle weakness plus skin rashes

Dermatomyositis is an inflammatory skin and muscle disease. Distinctive rashes on the hands, feet, elbows, face, and/or upper body, occurring along with muscle weakness, are hallmark symptoms. (Also see Autoimmune Diseases)

What is Polymyositis?

Inflammatory muscle weakness without skin rashes

Polymyositis is an inflammatory muscle disease. It's hallmark symptom is extreme muscle weakness, usually in the neck, upper arms, and thighs. When polymyositis occurs along with a skin rash, it is called dermatomyositis.

What is Polymyositis? It is a muscle disease featuring inflammation of the muscle fibers, typically those closest to the trunk or torso. This results in weakness that can be severe.

Symptoms of Dermatomyositis and Polymyositis

Dermatomyositis Symptoms
Polymyositis Symptoms

Diagnosis of Dermatomyositis and Polymyositis

Case Report: NXP-2 Positive Dermatomyositis: A Unique Clinical Presentation. Nuclear matrix protein (NXP-2) antibodies have been described as a myositis–specific antibody that may aid in the diagnostic evaluation. PubMed, Case Rep Rheumatol, 2017;2017:4817275.

State of the art on nailfold capillaroscopy (NFC) in dermatomyositis (DM) and polymyositis (PM). The overview confirms that NFC is a safe and noninvasive tool able to help the clinician in the diagnosis of DM and PM and to better characterize the phase of disease activity of these patients. PubMed, Semin Arthritis Rheum, 06/28/2017. (Also see Nailfold Capillaroscopy)

Mortality and Prognosis of DM/PM

Radiological images of interstitial pneumonia in mixed connective tissue disease (MCTD) compared with scleroderma (SSc) and polymyositis/dermatomyositis(PM/DM). HRCT images in MCTD patients can be classified as SSc pattern or PM/DM pattern. PubMed, Eur J Radiol, 2018 Oct;107:26-32. (Also see Correlation between Pulmonary Fibrosis and other Diseases and Mixed Connective Tissue Disease)

Anti-NT5C1A autoantibodies are associated with more severe disease in patients with juvenile myositis. As in adults with inclusion body myositis, patients with juvenile myositis with anti-NT5C1A autoantibodies have more severe disease. PubMed, Ann Rheum Dis, 2018 May;77(5):714-719.

Muscle biopsy in combination with myositis–specific autoantibodies aids prediction of outcomes in juvenile dermatomyositis. Muscle pathology, in combination with MSA, predicts the risk of remaining on treatment in JDM and may be useful for discussing probable treatment length with parents and patients. PubMed, Arthritis Rheumatol, 05/23/2016.

Cardiac abnormalities in adult patients with polymyositis (PM) or dermatomyositis (DM) as assessed by non-invasive modalities. Patients with PM or DM had an increased prevalence of cardiac abnormalities compared to healthy controls and left ventricular diastolic dysfunction was a common occurrence and correlated to disease duration. PubMed, Arthritis Care Res (Hoboken), 10/26/2015. (Also see Complications with Heart Involvement)

Serum progranulin (PGRN) levels are elevated in dermatomyositis (DM) patients with acute interstitial lung disease, predicting prognosis. Serum PGRN is associated with disease activity and prognosis of DM with interstitial lung disease. Arthritis Research and Therapy, 02/18/2015.

Treatments for Dermatomyositis and Polymyositis

Biological Agents
CB2 Agonist
Combination Therapies
Stem Cell Transplants


Serum level of DNase1l3 in patients with dermatomyositis/polymyositis (DM/PM), systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA), and its association with disease activity. A significant reduction was found in serum DNase1l3 level in DM/PM and SLE, which may associate with clinic features and disease activity. PubMed, Clin Exp Med, 12/30/2016. (Also see Research on Systemic Lupus Erythematosus and Causes of Rheumatoid Arthritis)

The Prevalence of Individual Histopathologic Features Varies according to Autoantibody Status in Muscle Biopsies from Patients with Dermatomyositis (DM). The prevalence of different histological features varies according to autoantibody status in DM and muscle biopsy features are similar in anti-Jo1 patients with and without a rash. Journal of Rheumatology, 07/14/2015.

Nailfold capillaroscopic changes in dermatomyositis (DM) and polymyositis (PM). Significant differences were observed between PM and DM with higher frequency and mean score of nailfold videocapillaroscopy changes in DM. PubMed, Clin Rheumatol, 2015 Feb;34(2):279-84.

Polymyositis: Can a gluten-free diet reduce symptoms? If you have polymyositis — a rare connective tissue disease — you may be at increased risk of celiac disease. In such cases, a gluten-free diet can improve signs and symptoms of celiac disease. But there's no evidence that a gluten-free diet can improve signs and symptoms of polymyositis. Mayo Clinic. (Also see Celiac Disease and Gluten Sensitivity)

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