Kidney non-tumor - Congenital anomalies

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Kidney non-tumor

Congenital anomalies

Reviewers: Nikhil Sangle, M.D. (see Reviewers page)
Revised: 11 April 2012, last major update April 2012
Copyright: (c) 2003-2012, PathologyOutlines.com, Inc.

General
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● 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 Jan 24 [Epub ahead of print])

Agenesis

General
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● 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’s (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

Case reports
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● 36 week gestational age male with Klinefelter’s syndrome and bilateral renal agenesis (Arch Pathol Lab Med 2004;128:e44)

Gross images
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Bilateral renal agenesis

1: posterior view of stillborn with no kidneys and downwardly displaced adrenal glands (arrows); 2: 47, XXY

Duplication of ureters

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

Gross images
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Left: duplication on right side; right: with obstructive renal dysplasia

Left: bilateral duplication; right: incomplete duplication

Ectopic (displaced) kidneys

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

Gross images
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Ectopic kidney

With multiple stones; medial portion

Horseshoe kidney

General
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● 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 Feb 17 [Epub ahead of print])
● Complete fusion of the kidneys produces a formless mass in the pelvis (pancake kidney)

Gross images
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Fusion at lower poles

Hypoplasia

General
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● 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

Diagrams / gross images
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Renal hypoplasia

Micro images
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Oligomeganephronic renal hypoplasia

Renal tubular dysgenesis

General
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● 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)

Micro images
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Various images

End of Kidney non-tumor > Congenital anomalies

Ref Updated: 4/6/12

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