[Spontaneous regression of pulmonary images interpreted as metastases of kidney cancer. Apropos of 2 cases].

The authors report two cases of spontaneous regression of pulmonary metastases from hypernephroma; this is an exceptional event that occurs in 0.8% of metastasized renal carcinomas; spontaneous regression in all cancers as a group occurs in 0.0014% of cases. The theories postulated up till now to explain this phenomenon are unconvincing. The authors suggest the possibility of tumorous emboli: this event, that occurs mainly in those carcinomas with a propensity for extension to veins, such as renal carcinoma, choriocarcinoma, hepatoma and liver metastases, does not necessarily give rise to a metastasis. The evidence that leads to advocate nephrectomy in metastasized renal carcinoma are recalled and discussed.