Definition, Etiology, DiagnosisTop
Medullary sponge kidney (MSK) is a kidney malformation of the terminal collecting ducts in the calyceal region. Etiology is unknown. About half of the patients have a family history of MSK but no definitive genetic cause has been found.
MSK is usually diagnosed in patients aged 20 to 50 years, often following IV pyelography performed for those presenting with renal colic. In others MSK may be detected incidentally due to the presence of numerous small calcifications of the renal medulla (nephrocalcinosis) visible on plain abdominal radiographs. Ultrasonography reveals multiple cysts 1 to 7 mm in diameter located in the inner parts of the renal medulla and accompanied by calcifications.
The main complications include kidney stones and urinary tract infections. MSK alone does not cause renal failure. In patients without clinical symptoms, no specific monitoring is required. In those with a history of nephrolithiasis, a full diagnostic workup for the causes of nephrolithiasis is indicated, with prophylaxis based on the results.