Mixed connective tissue disease presenting with recurrent rhabdomyolysis

We describe the case of a young woman with recurrent rhabdomyolysis caused by mixed connective tissue disease (MCTD). She initially presented with subacute progressive muscle weakness, myalgia, headache, fever, dark urine and diplopia. Examination revealed proximal muscle weakness, bilateral VI nerve palsies and mild periorbital oedema. Blood tests showed creatine kinase (CK) of 63 770 IU/L. Other investigations revealed aseptic meningitis, and pleural and pericardial effusions. Her anti-U1 ribonuclear protein antibody was positive. Detailed screening for other causes of rhabdomyolysis was negative, and muscle investigations (MRI and biopsy) were consistent with resolving rhabdomyolysis. She recovered fully, then experienced two further similar episodes in the following 9 months. She has been diagnosed with MCTD presenting with recurrent rhabdomyolysis. To our knowledge, this phenomenon has not been reported in the literature.