Development of multiple (>3) and bilateral renal cysts in patients whose CRF cannot be attributed to hereditary cystic disease.
>50% patients on dialysis for more than 4 years.
More common in males and African-American than Caucasian.
Clinical: Bilateral and asymptomatic in its early stages; cysts are present in 8% of patients at initiation of dialysis; 90% develop cysts after 10 years of dialysis.
Some cysts develop before dialysis, suggesting it's not only due to dialysis.
Mostly asymptomatic, some may present with abdominal pain and hematuria.
Cysts range from 0.5 - 3 cm in diameter.
Initially cortical in location, later medullary region too (image A).
Tubular cysts in medulla and cortex.
Cysts are lined by flattened cuboidal or columnar epithelium (image B).
Generally involve the proximal tubules of the kidney.
May have calcium oxalate crystal depositions.
Occasional cysts contain clear cells that are carbonic anhydrase IX+; may be a precursor of RCC.
Should be accompanied by other changes of dialysis (end-stage) kidneys (sclerosis, fibrosis, atrophy, etc.).
Complications: RCC (50-100X increased risk), intrarenal and retroperitoneal hemorrhage and cyst infection.
2-7% developed RCC, which include some unusual form (ACD-associated RCC and clear cell papillary RCC).
Large cysts require surgery to exclude RCC.