[A Case of Rectal Metastasis of Gastric Cancer Associated with Dermatomyositis].

We report a case of rectal metastasis of gastric cancer associated with dermatomyositis showing paraneoplastic syndrome. The patient was a 70-year-old man who had undergone curative total gastrectomy for Stage III Agastric cancer in March 2005. He was diagnosed with dermatomyositis and treated with prednisolone after gastrectomy. In April 2006, erythema of his face relapsed, and his serum CPK level was abnormally elevated. He experienced muscle weakness and dysphagia, and was treated with increased doses of prednisolone and gamma-globulin. At this time, endoscopic examination and computed tomography(CT)revealed a rectal tumor with hepatic metastasis. We performed Hartmann's operation in July 2006. The rectal tumor was predominantly submucosal, was 7 cm in diameter, involved #251 lymph node, and had positive peritoneal lavage cytology. The histopathological findings of the rectal tumor were comparable with those of gastric cancer, and we therefore diagnosed metastatic adenocarcinoma of gastric cancer. After surgery, we could control the patient's dermatomyositis with prednisolone at a reduced dose. However, chemotherapy with S-1 was ineffective and the patient died 8 months postoperatively.