Conclusions

Seronegative immune-mediated necrotizing myopathy should be considered in patients presenting with severe rhabdomyolysis and proximal weakness when common causes are excluded, and MRI suggests inflammatory myopathy. Accurate diagnosis of IMNM is essential, as management varies from traditional rhabdomyolysis. Further research is needed to determine alternative biomarkers in patients with seronegative IMNM, with some data suggesting anti-signal recognition particle antibody (anti-SRP) as a potential supplement.

This case report highlights the diagnostic approach to an atypical presentation of rhabdomyolysis. It is important to emphasize that our findings for this study did not include a definitive muscle biopsy; given the clinical features of this case, we maintain a high clinical suspicion of inflammatory myopathy.