[A metastatic muscle mass as the first manifestation of renal-cell cancer. A case report and review of the literature].

Although metastasis is relatively frequent in renal cell carcinoma (affecting mainly the lungs, lymphatic glands and bones), location of metastasis in muscles is extremely rare as in other oncological processes. The literature only offers isolated cases of renal cell carcinoma with metastasis in muscles, and no preferred muscular site is found in these cases nor is there any clear intrinsic relation to prognosis, having been described both at the onset an upon relapse of the oncological process. The intimate mechanism behind this infrequent metastatic site is unknown even today but it presents a series of specific and peculiar factors such as vascular flow, metabolism and oxygen tissue pressure which can negatively condition this process. We present the case of a 60-year-old patient who began with a mass in the triceps muscle. A biopsy confirmed its metastatic nature and indicated an asymptomatic renal cell carcinoma. Further complementary examinations showed metastasis in other muscle groups.