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Kidney nontumor / medical renal

Developmental & cystic diseases

Congenital anomalies-general

Author: Nikhil Sangle, M.D.

Last author update: 2 April 2012

Last staff update: 14 December 2023

Copyright: 2002-2025, PathologyOutlines.com, Inc.

PubMed Search: Kidney (congenital abnormalities [title])

Table of Contents

Cite this page: Sangle N. Congenital anomalies-general. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/kidneycongenital.html. Accessed January 12th, 2025.

Definition / general

10% of individuals have urinary tract malformations, although many are asymptomatic
15% of congenital urogenital anomalies are secondary to an underlying chromosomal disorder
In children, 20% of chronic renal failure is due to renal dysplasia or hypoplasia
In adults, 10% of chronic renal failure is due to adult polycystic kidney disease
Mass ultrasound screening detects congenital renal and urinary tract anomalies in 1% but not recommended since most would ultimately be detected via symptoms; most commonly vesicoureteral reflux, ureteropelvic junction obstruction, ectopic kidney, renal dysplasia (Pediatr Nephrol 2012;27:949)

Agenesis

Complete absence of renal tissue; unilateral or bilateral; 0.03% of newborns but 0.3% of stillborn
Bilateral agenesis: incompatible with life; associated with large adrenal glands; leads to Potter (oligohydramnios) sequence; possible causes include maternal insulin dependent diabetes mellitus and male sex of fetus but usually no specific etiology (PLoS One 2010;5:e12375)
Unilateral agenesis: not fatal

Duplication of ureters

< 1% of individuals
Usually asymptomatic; may be associated with obstruction

Ectopic (displaced) kidneys

Usually at pelvic brim, may have kinking of ureters (Urologia 2010;77:212, Clin Exp Nephrol 2009;13:531)

Horseshoe kidney

Most common congenital kidney anomaly, 0.15 - 0.25% of all newborns
90% are fused at lower pole
Associated with obstruction, anomalous superior vena cava (Circ J 2012;76:1253)
Complete fusion of the kidneys produces a formless mass in the pelvis (pancake kidney)

Hypoplasia

Rare; failure of kidney to develop to normal size without scarring
Usually unilateral with a reduced number of nephrons and pyramids (6 or less) but otherwise normal architecture
Associated with PAX2 mutations (J Am Soc Nephrol 2001;12:1769)
Oligomeganephronia: type of hypoplasia with small kidney but hypertrophied nephrons due to compensatory hypertrophy caused by reduced number of nephrons

Renal tubular dysgenesis

Rare congenital abnormality of renal development characterized by short and poorly developed proximal convoluted tubules without dysplasia or cystic disease (Hum Pathol 1986;17:1259)
Characterized by oligohydramnios and the Potter sequence, pulmonary hypoplasia, calvarial bone hypoplasia with enlarged fontanels
Causes: acquired (associated with renal hypoperfusion, Pediatr Dev Pathol 1999;2:25) or autosomal recessive (mutations in genes associated with angiotensinogen, renin, angiotensin converting enzyme or angiotensin II receptor type 1, J Am Soc Nephrol 2006;17:2253, Hum Mutat 2012;33:316)
Identified in 1% of perinatal autopsies in 1991 (Hum Pathol 1991;22:147)

Diagrams / tables

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