How simple are 'simple renal cysts'?

Abstract

The increasing use of medical imaging as an investigative tool is leading to the incidental and frequent finding of renal cysts in the general population. The presence of a solitary or multiple renal cysts has been generally considered benign in the absence of a family history of renal cystic disease or evidence of chronic kidney disease. Nonetheless, a number of recent studies have questioned this consensus by reported associations with the development of hypertension or malignant change. For these reasons, some clinicians consider the presence of renal cysts to be a contraindication to kidney donation. The situation is complicated by the different usage of the term 'simple' by some radiologists (to indicate non-complex lesions) or nephrologists (to indicate age-related non-hereditary lesions). We propose that the term 'simple' be replaced with the morphological description, Stage I renal cyst (Bosniak Classification). The presence of a Stage I renal cyst should not preclude kidney donation. However, occult renal disease should be excluded and appropriate donor assessment performed.

Keywords: ADPKD; acquired cystic disease; renal cell carcinoma; renal transplantation; simple renal cysts.

FIGURE 1:

Prevalence of Stage I renal cysts diagnosed on ultrasound in a healthy ageing population in Taiwan. Modified from [23].