Abstract
Renal endometriosis is a rare disease for which the mechanisms of pathogenesis are still unclear. As such, early diagnosis and an appropriate treatment are often delayed because of the tendency to be misdiagnosed as a renal tumor. In October 2013 we performed a radical nephrectomy for a 37-year-old woman with renal endometriosis who was preoperatively misdiagnosed as having a right renal tumor. Avoiding the misdiagnosis of renal endometriosis requires a detailed case history, especially regarding whether the cyclicity of lumbodorsal pain and hematuria correlates with patients' menstrual cycles. Imaging examinations are commonly helpful for localization, whereas relieving symptoms with drugs to create a hypoestrogenic state is useful for clinical diagnosis. However, a final diagnosis for renal endometriosis still must depend on histopathologic examination.