Necrotizing myopathy as a paraneoplastic syndrome associated with renal cell carcinoma.

We report a 49-year-old patient with necrotizing myopathy and a right renal mass. After laparoscopic radical nephrectomy, a remission of myopathy was seen. Pathologic evaluation of the nephrectomy specimen revealed a clear cell renal cell carcinoma. Relapse of myopathy 6 months postoperatively coincided with the diagnosis of the appearance of liver metastatic disease. After initiation of treatment with an mTOR-inhibitor, myopathy became less active requiring smaller amounts of corticosteroids with a complete remission of myopathy after 3 months of systemic treatment for metastatic renal cell cancer.