A Review of the Natural Progression of Medullary Sponge Kidney and a Novel Grading System Based on Intravenous Urography Findings

Abstract

Purpose: Medullary sponge kidney (MSK) is a developmental abnormality of the medullary pyramids of the kidney, characterised by cystic dilatations of the collecting ducts. We investigated a cohort of patients with MSK to gain further information about its presentation, clinical course and treatment required. We devised a grading system based upon findings at diagnostic intravenous urography (IVU) and established a relationship between severity of IVU findings and severity of disease. Materials and Methods: The clinical notes and imaging of 29 patients with MSK were analysed. The severity of IVU findings was classified as follows: grade 1 (one calyx, unilateral), grade 2 (one calyx, bilateral), grade 3 (more than one calyx, unilateral) and grade 4 (more than one calyx, bilateral). Results: The age range at diagnosis was 12–69 (mean 39), mean follow-up period was 12.7 years. Increasing grade of IVU findings correlated with more frequent symptomatic stone episodes (grade 1: 0.09 episodes per patient per year; grade 4: 0.34). Higher grade was also related to the number of hospital admissions (grade 1: 0.182 per patient per year; grade 4: 0.282) and the number of procedures required (either surgery or extracorporeal shock wave lithotripsy; grade 1: 0.0 interventions per patient per year; grade 4: 0.24). Conclusions: MSK presents over a wide age range and can cause long periods of intermittent episodes. Patients can be graded using a novel system based on IVU findings, which correlates with severity of disease. Management strategies such as intensity of follow-up can be modified using this grading.

CT Urography for the Diagnosis of Medullary Sponge Kidney

“…Moreover, it has been shown that radiographic findings also have prognostic importance. In a retrospective study, Forster et al [24 ]showed a strong correlation of the severity of radiologic and clinical features in MSK.…”

MR Imaging of Focal Medullary Sponge Kidney: Case Report

“…1,2 Morbidity is estimated at one in 5,000 to 20,000 people. 8 Although most patients with MSK remain asymptomatic, 2.6 to 20z demonstrate clinical symptoms, such as renal colic, urinary tract infection, and macrohematuria due to urinary stones. 2,9 Therefore, MSK is mainly diagnosed by kidney-ureter-bladder radiography (KUB) and IVU.…”

Medullary Sponge Kidney Associated With Multivessel Fibromuscular Dysplasia: Report of a Case With Renovascular Hypertension

“…8 FMD tends to affect young to middle age white women and may involve almost any artery as well as multiple arterial beds. 9,10 Often, bilateral renal, splanchnic, extremities, and asymptomatic cerebrovascular involvement is found during angiographic investigation.…”