A case of sigmoid colon cancer with polymyositis

Abstract

A 70-year-old man developed proximal limb muscle pain and difficulty moving. He was diagnosed with rhabdomyolysis due to high serum creatine phosphokinase (CK) and creatinine levels. He was treated with rest and intravenous fluids, but was left with some muscle weakness and dysphagia. Therefore, he was referred to our hospital ; diagnosis of polymyositis was made based on his high CK level (3,059 IU/l), electromyogram, and femoral muscle MRI. He was also diagnosed as having sigmoid colon cancer and liver metastasis based on abdominal CT scan and colonoscopy results. He was thought that his polymyositis might have been due to his colon cancer. He had a sigmoidectomy and hepatectomy. After surgery his CK level immediately decreased to 585 IU/l and normalized over 3 months. His muscle strength gradually improved. It is known that dermatomyositis and malignancy can occur concominantly. However, polymyositis present concomitantly with colon cancer is rare.