A case of anti cavin 4 immune mediated rippling muscle disease and myasthenia gravis

<h3>Background and Aim</h3> Rippling muscle disease is an extremely rare myopathy, presenting with symptoms and signs of muscular hyperexcitability including wave-like contractions and visible percussion- induced rippling of the muscles. CAV3 mutations have been linked to the genetic form of this condition, but recently an autoimmune variant has been described, which is associated with anti-cavin-4 IgG autoantibodies and occurs most frequently in myasthenics. <h3>Case report</h3> An 81 year old gentleman presented with generalised myasthenia gravis 13 years ago. He was treated with steroids and methotrexate to good effect, but was subsequently diagnosed with lung cancer; he underwent lobectomy and contemporaneous thymectomy, and was switched to mycophenolate. Mycophenolate maintained remission but caused gastrointestinal side- effects, and so after some years was stopped. Shortly after stopping mycophenolate he started to experience calf muscle spasms and visible muscle rippling, but no myasthenic symptoms. Over the following months things deteriorated to include painful whole-body and facial spasms. He was restarted on 60 mg prednisolone, with rapid resolution of symptoms; anti- cavin-4 antibodies returned positive. Prednisolone was weaned, with only a low dose required to maintain remission. <h3>Conclusion</h3> Anti-cavin-4 mediated RMD is an extremely rare autoimmune myopathy associated with myasthenia gravis which typically responses well to immunotherapy.