Acute Muscle Injury and Subcutaneous Edema in a Patient with Anti-nuclear Matrix Protein-2 Antibody Positive Dermatomyositis Sine Dermatitis.
Emi Minekawa, Yohsuke Oto, Yoshinao Muro et al.
✦ AI-curated · Sources linked
Case in brief
A patient with anti-NXP-2 antibody-positive dermatomyositis sine dermatitis presented with acute muscle injury and marked creatine kinase elevation, without a skin rash. The clinical course and imaging resembled drug-induced rhabdomyolysis, and the patient initially improved with hydration. Subsequent respiratory failure prompted further evaluation; muscle biopsy and antibody testing established the diagnosis. The case illustrates how this form of myositis can be difficult to distinguish from rhabdomyolysis when skin findings are absent and muscle enzyme elevation is acute and transient.
What made this case unusual
The combination of absent dermatitis, acute marked CK elevation, and rhabdomyolysis-like imaging obscured anti-NXP-2-positive dermatomyositis; respiratory failure emerged after initial improvement with hydration.
Diagnostic / clinical pearl
In suspected myositis without a rash, rhabdomyolysis-like imaging and acute CK elevation do not exclude dermatomyositis sine dermatitis. Muscle biopsy and antibody testing can be important when the distinction remains unclear.