It is well documented that clear cell carcinomas of the kidney (hypernephromas) regress under certain circumstances. Bartley and Hultquist clearly illustrated this when they reviewed the literature and reported 26 of their own cases in 1950.19
It is also known that, in some instances, distant metastases of clear cell carcinomas of the kidney have been known to regress or disappear.38,39 Everson40 reviewed and collected 21 acceptable cases of spontaneous regression of hypernephromas in 1964. Everson et al carefully documented 31 cases in 1966.22 We have recently reviewed our own experiences37 and described two new cases of regression of pulmonary metastases, and one case of regression of bony metastases.
Most reported regressions have been pulmonary metastases where the diagnosis was presumptive and where microscopic study of the pulmonary lesion was not available. This has led some observers to question whether or not these "regressed" pulmonary metastases