Supplemental Material for: Late-onset MuSK myasthenia gravis in a patient with poly-autoimmunity: case report and literature review

Although MG may occasionally co-occur with other autoimmune conditions, the presence of multiple autoimmune diseases, termed poly-autoimmunity, is rare and presents significant diagnostic and therapeutic challenges.</p><p dir="ltr"><b>Case Presentation</b></p><p dir="ltr">We describe the case of a 79-year-old woman with longstanding autoimmune thyroiditis and Sjögren’s syndrome who presented with severe bulbar and axial weakness.

Initially suspected to have a Sjögren’s-associated myopathy, she was later diagnosed with MuSK MG. Early empirical treatment with intravenous immunoglobulin was followed by rituximab, resulting in marked clinical improvement and sustained remission more than a year later during follow up. Concurrently, she was diagnosed with latent autoimmune diabetes in adults (LADA), raising her autoimmune burden to four counts.</p><p dir="ltr"><b>Conclusion</b></p><p dir="ltr">This case underscores the importance of clinical vigilance and multidisciplinary evaluation in patients with poly-autoimmunity and highlights the potential for personalised, mechanism-driven therapeutic approaches.</p>