A 72-year-old man with a history of prostate cancer presented 7 years postradiotherapy with a painless, egg-sized, rapidly growing nodule on the left groin at the radiation site. He underwent left high orchiectomy under a diagnosis of groin lymph node metastasis of prostate cancer. The tumour had penetrated deep into the internal inguinal ring and was resected as proximally as possible to the internal ring with a positive surgical margin. Macroscopically, the left testis was intact in the resected specimen. Immunohistochemical staining revealed that the tumour consisted of myxofibrosarcoma (MFS) with spindle cells; and was positive for vimentin, cytokeratin (AE1/AE3), MIB-1 and CD68, and negative for α-SMA, S-100, CD34 and myogenin. Thus, the tumour was diagnosed as high-grade MFS of the spermatic cord. Postoperative CT revealed a right renal tumour and adrenal tumour. Right radial nephrectomy was performed and the patient was doing well at 10-month follow-up.