Pediatric Medullary Sponge Kidney Workup

Updated: Aug 28, 2021
  • Author: Howard Trachtman, MD; Chief Editor: Craig B Langman, MD  more...
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Workup

Laboratory Studies

In patients with medullary sponge kidney (MSK) and hemihypertrophy, serial screening should be performed to exclude malignancies, including abdominal tumors. The following studies are also indicated:

  • Urinalysis (ie, assessment of urinary calcium excretion, urine culture)

  • A 24-hour urine collection for calcium, magnesium, and citrate: Patients with medullary sponge kidney may have high excretion of lithogenic molecules or low excretion of urinary inhibitors of stone formation.

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Imaging Studies

Intravenous pyelography reveals radial, linear striations in the papillae or cystic collections of contrast material in ectatic collecting ducts. The result is a characteristic blushlike pattern to the papillae, the so-called "bouquet of flowers" or "paintbrush" appearance. Typical cases involve all renal papillae but medullary sponge kidney may be unilateral or may affect only a few papillae. Declining use of intravenous pyelography as an imaging technique may result in underdiagnosis of medullary sponge kidney cases.

Renal ultrasonography and CT scanning are unnecessary except to distinguish medullary sponge kidney from papillary necrosis or autosomal dominant polycystic kidney disease.

Intravenous pyelography remains the first-line imaging study for the diagnosis of medullary sponge kidney; however, Pisani et al identified four ultrasonographic findings that can help support the diagnosis, when coupled with clinical findings. [11] These ultrasound findings are as follows:

  • Hypoechoic medullary areas
  • Hyperechoic spots
  • Microcystic dilatation of papillary zone
  • Multiple calcifications (linear, small stones or calcified intracystic sediment) in each papilla

The role of MRI is unknown.

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Other Tests and Procedures

Other tests

Appropriate workup is needed if medullary sponge kidney appears to be associated with another condition, such as hemihypertrophy or pyloric stenosis, or is part of a syndrome, such as Marfan or Ehlers-Danlos syndrome. This testing should be performed to exclude the presence of a malignancy.

Procedures

No additional, specific diagnostic procedures are warranted for diagnostic evaluation.

Histologic findings

Neither renal biopsy nor nephrectomy is routinely performed.

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