Inflammatory myositis complicating hypocomplementemic urticarial vasculitis despite on-going immunosuppression

We present a patient with previously diagnosed hypocomplementemic urticarial vasculitis syndrome, with skin, lung, and renal involvement, who presented with congestive cardiac failure. During the course of her hospitalization, she was also found to have profound proximal muscle weakness in both upper and lower limbs associated with raised creatinine kinase levels. A muscle biopsy was performed, which demonstrated evidence of an inflammatory myositis with vasculitis, which had returned despite on-going immunosuppression. This occurrence of a new autoimmune disease may well be an example of the "waste disposal" hypothesis.