Kidney Cysts

Kidney cysts are fluid-filled sacs that form on or within the kidneys. They fall into two main categories: simple cysts, which are benign and extremely common, and complex or polycystic cysts, which can signal a more serious inherited disorder. The prevalence of simple renal cysts is approximately 7.7% to 11.9% when detected by ultrasound, and as high as 27% to 41% when detected by CT imaging, which captures smaller cysts that ultrasound misses. Prevalence increases sharply with age — ranging from about 2.4% in the second decade of life to more than 35% in the seventh decade and beyond — and is nearly three times more common in men than in women. Most simple cysts cause no symptoms, require no treatment, and are discovered incidentally during imaging for unrelated conditions. The more serious form, autosomal dominant polycystic kidney disease (ADPKD), is a genetic condition involving progressive cyst growth throughout both kidneys. ADPKD affects 1 in 400 to 1,000 people, making it the most common genetic cause of renal failure worldwide, and accounts for 6% to 10% of all patients on dialysis in the United States. Management of simple cysts is typically watchful waiting, while ADPKD requires ongoing monitoring and, in advanced cases, dialysis or kidney transplantation.