Medullary sponge kidney

Contributors: Cafer Zorkun M.D., PhD.

Overview
Medullary sponge kidney is a congenital disorder of the kidneys characterized by a cystic dilatation of the collecting tubules in one or both kidneys.

Incidence
It has been estimated to occur with a prevalence of between 1 in every 5,000-10,000 individuals in a population.

Clinical Presentations
In most cases, medullary sponge kidney affects only one kidney, in which case kidney function is usually preserved and individuals may be asymptomatic. However, these individuals are at increased risk for nephrolithiasis (kidney stones) and urinary tract infection.

Ultrasonography

 * Echogenic medullary pyramids in patients with medullary sponge kidney, irrespective of the presence of medullary nephrocalcinosis.
 * US findings can demonstrate complications related to calculus disease.

Computed Tomography

 * Unenhanced CT scan findings may be normal or demonstrate medullary nephrocalcinosis.
 * Enhanced scans may demonstrate contrast accumulation within the papillae.

Patient #1

Images courtesy of RadsWiki

Complications
Complications such as infection, hematuria, and nephrolithiasis may be the presenting complaint in approximately 10% of patients.