Nephrogenic adenoma arising in a renal cortical cyst.

Nephrogenic adenoma is an unusual lesion of the urinary tract first described by Davis in 1949 as a hamartoma. In 1950, Friedman and Kuhlenbeck subsequently characterized the lesion in more detail and named it nephrogenic adenoma. It appears to be a metaplastic response of the urothelium elicited by trauma and chronic irritation and is considered to be benign. A MEDLINE search of the literature from 1960 to the present revealed no previous documentation of a nephrogenic adenoma arising from a renal cortical cyst. Herein, we present such a case arising in a renal cortical cyst.