[Extrarenal manifestations of renal cell carcinoma: the primary metastatic lesion (author's transl)].

In 18 patients, histologic evaluation of a solitary distant metastasis with characteristic hypernephroid pattern subsequently led to the diagnosis of renal cell carcinoma. The metastatic lesion was treated surgically in 15 cases; 14 patients underwent radical surgery and one patient with a solitary kidney underwent partial nephrectomy. Osseous metastases were predominant (12 out of 18). There was an excellent morphologic agreement between metastatic and primary lesions: in no case were metastases less differentiated than the primary tumor. Therefore in all cases of metastases with hypernephroid structures an aggressive search for renal malignancy is required. Five-year survival was 5% and identical to a group of 61 patients with metastases and a symptomatic renal cell carcinoma at diagnosis. The poor prognosis was not influenced by surgical extirpation of the solitary metastasis.