Dermatomyositis — SCE Rheumatology MCQ

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EasyConnective tissue diseasesDermatomyositisSCE Rheumatology

A 46-year-old woman has progressive difficulty climbing stairs and a rash over her hands. Examination shows Gottron papules and a heliotrope rash. Investigations show a creatine kinase concentration of 6200 IU/L, and electromyography demonstrates myopathic changes. What is the most likely diagnosis?

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Correct answer: A — Dermatomyositis

The diagnosis is dermatomyositis. Progressive proximal muscle weakness, reflected by difficulty climbing stairs, together with markedly elevated CK and myopathic EMG changes establishes an inflammatory myopathy phenotype. Gottron papules and a heliotrope rash are the decisive characteristic cutaneous manifestations identifying dermatomyositis. Polymyositis may cause proximal weakness and elevated CK but does not produce these dermatomyositis-specific skin lesions. Hypothyroid and drug-induced myopathies can also cause weakness and CK elevation but would require the relevant endocrine or medication history and do not explain the characteristic rash. Inclusion body myositis usually develops after age 50, often with asymmetric finger-flexor and quadriceps weakness, and lacks the classic dermatomyositis eruption.

Reference: Didona D, Juratli HA, Scarsella L, et al. The polymorphous spectrum of dermatomyositis: classic features, newly described skin lesions, and rare variants. European Journal of Dermatology. 2020;30(3):229-242. https://pubmed.ncbi.nlm.nih.gov/32666925/