Medullary sponge kidney (MSK) is a rare, developmental abnormality characterized 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 radiologic 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), hematuria (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, characterized 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.
History and exam
Other diagnostic factors
- previous nephrolithiasis
- flank pain
- costovertebral angle tenderness
- urinary urgency
- increased frequency of urination
- groin pain
- Beckwith-Wiedemann syndrome
- Caroli disease
- congenital hepatic fibrosis
- Ehlers-Danlos syndrome
- family history of polycystic kidney disease
- chronic kidney disease
- female sex
1st investigations to order
- urine culture
- BUN and creatinine
- serum electrolytes
- abdominal radiography
- renal ultrasound
- intravenous urography
- noncontrast CT scan
- CT urogram
Investigations to consider
- 24-hour urine monitoring
- stone analysis
with urinary tract infection (UTI)
- Distal renal tubular acidosis
- Renal papillary necrosis
- Tuberculosis of kidney
- Guidelines on urolithiasis
- Surgical management of stones: AUA/Endourological Society guideline
Kidney stonesMore Patient leaflets
- Log in or subscribe to access all of BMJ Best Practice
Use of this content is subject to our disclaimer