Contents
Congenital disorder of the kidneys characterized by cystic dilatation of the collecting tubules in one or both kidneys.
History:
The introduction of radiological contrast media and IV urography in clinical diagnostics in the 1930s enabled the discovery of several diseases, including the medullary sponge kidney (MSK). MSK is a renal malformation characterized by cystic anomalies of precalyceal ducts, which is frequently associated with nephrocalcinosis and renal stones. Although it was first recognized by G Lenarduzzi in 1939, its thorough description was the result of the ante litteram multidisciplinary cooperation between a radiologist (Lenarduzzi), a urologist (Cacchi), and a pathologist (Ricci), all at the Padua University Hospital. These authors ‘established’ the paradigm for its diagnosis that is still used today Lenarduzzi-Cacchi-Ricci disease
Clinical features
- Hematuria
- Renal colic
- Fever
- Dysuria
Complications:
- Recurrent urinary tract infections (UTI)
- Nephrolithiasis and nephrocalcinosis
- Type I (distal) renal tubular acidosis (dRTA)
- Hypocitraturia
- Long-term bone loss (d/t persistent renal leak type hypercalciuria)
Diagnosis
24-hour urine test:
Recommended to help optimize the urinary chemistry in motivated patients with medullary sponge kidney who develop stones
- Renal leak type hypercalciuria
- Hypocitraturia
USG/X-ray
- Kidneys with hyperdense papillae with clusters of small stones
IV urogram (IVU)
GOLD STANDARD
- “Paintbrush-like” or “feathered” appearance of irregular (ectatic) collecting ducts
- At interface of papilla & calyx
- Cystic collections of ectatic collecting ducts like “bunches of grapes” or “bouquet of flowers“

CT-urogram:

Differential diagnosis:
Other causes of medullary nephrocalcinosis (deposition of calcium salts in medulla of kidney)
- Hyperparathyroidism
- Renal tubular acidosis type I
- Hypervitaminosis D
- Milk-alkali syndrome
- Sarcoidosis
Management
Treatment consists of managing the complications of medullary sponge kidney.
UTI management:
- Antibiotics
- Meticulous personal hygiene practices
Calcium stone management:
Most of the stones in patients with medullary sponge kidney tend to be small and will usually pass spontaneously, but occasionally surgery, ureteroscopy, or lithotripsy may be needed.
- High fluid intake (sufficient to generate 2000 mL/day urine)
- Dietary changes: Low in sodium, normal in calcium, high in potassium, and low to normal in protein
- Potassium citrate supplementation (minimize long-term bone loss)
- Bicarbonate supplements (↑ bone calcium)
Type I (distal) RTA:
- Alkali therapy (replenish HCO3–)
- K3-citrate supplementation (correct hypokalemia)