What distinguishes dermatomyositis from polymyositis?

Dermatomyositis has characteristic skin findings (Gottron's papules, heliotrope rash, V-sign, shawl sign) and higher malignancy risk. Polymyositis is now considered a diagnosis of exclusion. Both show proximal muscle weakness and elevated CK.

What is antisynthetase syndrome?

Antisynthetase syndrome: anti-aminoacyl-tRNA synthetase antibodies (anti-Jo-1 most common) + myositis + ILD + mechanic's hands + Raynaud + inflammatory arthritis. ILD is the major morbidity driver.

Which myositis-specific antibodies are associated with malignancy?

Anti-TIF1-gamma and anti-NXP2 are most strongly associated with cancer-associated myositis, especially dermatomyositis. Age >40, dysphagia, and rapid onset increase malignancy risk.

Myositis Disease Activity Score (MDAS)

Calculate the Myositis Disease Activity Assessment (MDAA) score for inflammatory myopathies (dermatomyositis, polymyositis, inclusion body myositis). Assesses muscle strength, skin disease, pulmonary, cardiovascular, and GI involvement.

⚕ Clinical Disclaimer: These calculators are for educational and reference purposes only. Always verify results with qualified clinical judgment and current clinical guidelines. Do not use as a sole basis for medical decisions.

How to Use

Enter the values for the scenario you are assessing. Calculate the Myositis Disease Activity Assessment (MDAA) score for inflammatory myopathies (dermatomyositis, polymyositis, inclusion body myositis). Assesses muscle strength, skin disease, pulmonary, cardiovascular, and GI involvement. Use the myositis das result to inform your calculation.

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