Medullary sponge kidney

Medullary sponge kidney (MSK) is a rare, developmental abnormality characterised by ectatic (dilatory) or cystic malformations in the medullary collecting ducts of the kidney resulting in medullary cysts.

Most patients are asymptomatic and the condition may be diagnosed based on incidental findings following radiological investigation for other reasons.

May be present in 3% to 20% of patients with renal stones.

May present with flank pain, recurrent urinary tract infections (UTIs), haematuria (gross and microscopic), nephrolithiasis, and nephrocalcinosis.

No specific treatment, and for many patients the condition is normally benign. For patients with symptoms, treatment focuses on treating UTI, removing kidney stones, and preventing recurrent infections and stones.

MSK is a rare, developmental abnormality that can occur in one or both kidneys, characterised by ectatic or cystic malformations in the medullary collecting ducts. The medullary cysts can range from 1 to 7 mm in diameter. Their presence gives the medulla a sponge-like appearance. Most patients are asymptomatic.