Metastasis from Renal Cell Carcinoma Presenting as Skeletal Muscle Mass: a Case Report

Renal cell carcinoma can metastasize to virtually any site. Skeletal muscle metastasis is not common. The correct diagnosis of metastatic renal cell carcinoma to skeletal muscle is difficult in comparison with soft-tissue metastasis diagnosis. We report the case of a 58-year-old man with skeletal muscle metastasis from a clear-type renal cell carcinoma 5 years after total nephrectomy. The tumour was located in the proximal left tight at the level of the great adductor muscle. Clinical work-up included both 18 fluorodeoxyglucose positron emission tomography combined with non-contrast computed tomography and magnetic resonance imaging. The mass was widely excised and was confirmed to be a metastasis from renal cell carcinoma. Maintaining a high degree of suspicion of metastatic renal cell carcinoma is required for patients with a history of renal cell carcinoma. Positron emission tomography, combined with computed tomography, appears to be an effective surveillance tool. Magnetic resonance imaging is helpful in the differential diagnosis from primary soft-tissue tumours.