[Primary pleomorphic rhabdomyosarcoma of the kidney in adults: unusual tumor].

Primary rhabdomyosarcoma (RMS) of the kidney in an adult is a very rare and unusual tumor in this site. The clinical signs associated with the flank tumoral syndrome, the histologic appearance of cytoplasmic double striation in rhabdomyoblasts and the immunohistochemical expression of skeletal muscle differentiation (desmin, myoglobin, myogenin) are described in the context of a rapidly evolving renal RMS in a 77-year old man. The differential diagnosis are mainly represented by sarcomatoid renal cell carcinoma. According to the neoplastic extent, the treatment includes radical nephrectomy, chemotherapy and surgery. The prognosis of primary renal RMS is extremely poor, with lymph node, hepatic, bone marrow and pulmonary metastasis and a short survival rate.