Clinical subsets of adult onset dermatomyositis defined by the MSA antibodies

Sharing is caring!

Clinical subsets of adult onset dermatomyositis defined by the MSA antibodies

• Anti-Mi-2 (nucleosome remodeling-deacetylase [NuRD]): seen in 10%–15% of DM patients. Patients present with acute onset of classic skin (V- and shawl-sign), periungual/cuticle overgrowth, and muscle features of DM. Not associated with malignancy or ILD. Manifestations respond very well to corticosteroids (CS) with 5YS over 90%. The autoantibody targets the chromodomain helicase DNA-binding protein, which is a part of the NuRD complex that participates in the remodeling of chromatin by deacetylating histones. Patients have a positive antinuclear antibody (ANA) with speckled pattern.

• Anti-melanoma differentiation-associated gene 5 (MDA-5) (clinically amyopathic DM [CADM]-140): seen in 5% to 10% of European/American DM patients and 10% to 50% of Asian DM patients. Patients present with ulcerations (nailfolds, over joints, oral), palmar papules, arthritis (60%), fever (60%), and rapidly progressive ILD (50%). Some patients (20%) have CADM (hence the name of the autoantibody, anti-CADM) although CPK, aldolase, and muscle MRI can be abnormal. The overall prognosis is poor depending on the response to ILD therapy. This MSA targets the melanoma differentiation-associated gene 5 protein which is a cytoplasmic RNA helicase that has an important role in the innate immune system response during RNA viral infections. ANA is negative although 30% have antibodies against SSA/Ro (52kD), which is a cytoplasmic antigen.

• Anti-TIF-1γ (p155/140): seen in 13% to 40% of DM patients who are typically aged over 60 years. It is highly associated with cancer. The sensitivity for diagnosing cancer-associated DM is up to 78% and specificity is 89%. The diagnostic odds ratio is 27, with a positive and negative predictive value of 58% and 95%, respectively. Patients usually present with classic DM rash that is frequently severe. Muscle disease may be low grade with normal CPK and elevated aldolase. The autoantibody targets TIF-1 family proteins, especially TIF-1γ. Notably TIF-1 proteins are interferon-responsive and have both positive and negative roles in carcinogenesis including p53 (tumor suppressor) regulation. Patients have a low-titer positive ANA with a speckled and homogenous pattern.

• Anti-nuclear matrix protein 2 (NXP2 or MJ, p140): seen in 2% to 17% of DM patients. Patient presents with classic DM rash. May have fingertip ulcerations. Subcutaneous calcifications common. Muscle disease is usually mild with normal CPK although muscle MRI may be abnormal (33%). In older patients, it is associated with underlying malignancy. The autoantibody targets the p140 NXP2.

• Anti-SAE (small ubiquitin-like modifier-1 activating enzyme or SUMO): seen in <8% and <3% of European and Asian DM patients, respectively. Patients present with DM rash and later get mild myositis (60%). Asian patients can get dysphagia and ILD. Rare to get other manifestations and there is no association with malignancy. The autoantibody targets the small ubiquitin-like modifier-activating enzyme.

Sharing is caring!

You cannot copy content of this page


Sign up to receive the trending updates and tons of Health Tips

Join SeekhealthZ and never miss the latest health information

Scroll to Top