17 December 2025
: Case report 
COVID-19-Associated MDA5-Mediated Necrotizing Myositis
Challenging differential diagnosis, Unusual or unexpected effect of treatment, Rare disease
Sarah Steadman ABCDEF 1, Amit Sikder ABCDEF 2, Harsh R. Desai
ABCDEF 3*, Bradley Collins BE 4, Tiffany Baker BDE 5, Julie Worthington ABCDEF 6
DOI: 10.12659/AJCR.949788
Am J Case Rep 2025; 26:e949788
Figure 1 Hematoxylin and eosin-stained sections from formalin-fixed paraffin-embedded skeletal muscle tissue shows myofibers at different stages of degeneration and regeneration, including necrosis (*), myophagocytosis (**), and basophilic fibers (*** left of basophilic fibers). These changes affected a minority of the muscle tissue and were diffusely distributed throughout the muscle fascicles, without an obvious perifascicular pattern. There was no significant lymphocytic inflammation (200× total magnification).