Dermatomyositis (DM) and Polymyositis (PM): Pathogenesis and clinical findings
Elevated Antinuclear Antibodies: Anti-Jo-1, Anti-OJ, Anti-Mi2, Anti-SRP, Anti-EJ, Anti-PL12, Anti-PL7
Demographics:
- F:M, 2:1
- Bimodal age distribution:
- Juvenile: 7 years of age (mean)
- Adult: 52 years of age (mean)
Perivascular, Capillary necrosis ->
- These processes occur in the skin on the dorsum of the hands, forming hyperkeratotic flat red papules -> Gottron Papules
- These processes occur in the upper & lower eyelids, causing red-purple discoloration +/- swelling -> Heliotrope Rash
- Dysphagia
- Aspiration, respiratory compromise
- Atrioventricular defects, tachyarrhythmias, dilated cardiomyopathy
- Elevation of muscle enzyme levels in serum: Creatinine kinase (CK), lactate dehydrogenase (LD), aldolase, aspartate aminotransferase (AST), and alanine aminotransferase (ALT)
- Muscle Biopsy Findings: Muscle necrosis, fiber regeneration, diffuse CD8+ T lymphocytes infiltrates
- Bilateral Muscle Weakness: Subacute development, primarily deltoids and hip flexors affected
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