ANTI-MDA5 DERMATOMYOSITIS
Cutaneous manifestations:
• Periorbital heliotrope (blue-purple) rash with edema
• Erythematous rash on the face, or the anterior chest (in a V-sign), and back and shoulders (in a shawl sign)
• Violaceous papules or plaques located on the dorsal part of the MCP or interphalangeal joints: Gottron’s papules
• Inverse Gottron’s sign
• Cracked palmar fingertips ("mechanic’s hands")
• Palmar papules: can be associated with hyperkeratosis, and complicated of ulcerations
• Skin ulcerations
• Auricular skin lesions: antihelix/helix violaceous macules and erythematous auricular papules
Clinical and Biological Features of Anti-MDA5 Dermatomyositis
• Fever: up to 74% of anti-MDA5 DM at onset [33-74%]
• Blood tests: Elevated ferritinemia, with no significant elevation of C-reactive protein.
Ferritin levels correlate with the severity of the disease and ILD
• Liver dysfunction: elevated levels of ALT or GGT, without elevated creatine kinase.
Liver biopsies show steatosis and hepatocyte ballooning
Ferritinemia increases and ILD worsens
Decreased CD4+ and CD8+ T cell counts and a raised CD4+/CD8+ ratio are frequently described
Association of Anti-MDA5 Dermatomyositis With Malignancy:
Associated with Malignancy:
• Anti-TIF1y Abs, and to a lesser extent, DM with anti-NXP2 Abs
Lung Manifestations of Anti-MDA5 Dermatomyositis
• Anti-MDA5 DM is associated with poor prognosis due to a high prevalence of RP-ILD
Phenotype 1
• Women
• ~20% of cases
• Arthralgia/arthritis
Phenotype 2
• Men
• ~50% of cases
• Skin vasculopathies
• Proximal muscle weakness
Phenotype 3
• Women
• ~30% of cases
• Mechanic's hands
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