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79 Cards in this Set

  • Front
  • Back
More than __percent of abdominal masses in neonates are due to congenital anomalies of the kidney and urinary tract
more than 50%
Potter's Sequence (aka__)
- aka oligohydraminos sequence
- beak-like nose
- low-set ears
- receding chin
- pulmonary hypoplasia
- abnormally bent lower extremities and contractures

Due to decreased or loss of normal cushioning amniotic fluid
Pulmonary hypoplasia seen in Potter's sequence is due to __
- lack of maturational stimulation provided by amniotic fluid
- chest wall compression due to lack of cushioning by amniotic fluid
- diaphram elevation by enlarged kidneys
Renal agenesis
- COMPLETE absence of any renal tissue
- unilateral or bilateral
- bilateral usually stillborn with Potter's sequence
- unilateral - at increased risk for development of renal failure later in life due to secondary focal segmental glomerulosclerosis (seen in the overworking compensating kidney)
Major DDX for bilateral renal agenesis is __
bilateral aplastic dysplasia
- very small amount of malformed renal tissue may not be apparent grossly and only found on micorscopic exam of the expected kidney site

- presence of any renal tissue, normal or dysplastic, rules out congenital renal agenesis
Likely cause of renal agenesis is failure of the ___ to develop from the mesonephric duct
- ureteric bud
- the ureteric bud arises from the mesonephric duct
- it induces differention of the metanephric blastema (part of the metanophros, the direct precursor to the kidney) into renal parenchyma
Maternal risk factors for development of renal agenesis in a child are __, ___, and __
- diabetes
- alcohol
- age < 18
Renal hypoplasia is __
reduction in renal mass due to too little genesis or NORMAL renal tissue
Simple versus oligomeganephronic hypoplasia
- no histologic abnormalities, just too little renal tissue

- marked compensatory hypertrophy due to overwork as a result of reduced number of nephrons

simple hypoplasia is rare compared to oligomeganephronic hypoplasia
In renal hypoplasia, renal function is stable in early childhood, but -...
may decline in late childhood and early adulthood due to secondary focal segmental glomerulosclerosis (proteinuria)
Renal hypoplasia can be an ___ event or occur as part of a ___
- isolated event
- part of a syndrome (renal-coloboma syndrome)
coloboma (greek:___)
- unfinished
- affects various parts of the eye
renal dysplasia is ___
- aberrant differentiation of renal parenchyma that does not proceed beyond the production of undifferentiated tubular structures surrounded by primitive mesenchyme
- +/- divergent differentiation too (heterotopia), such as cartilage

- abn tubular structures may develop into cysts (note: cysts are no required for the diagnosis of renal dysplasia)
Patterns of renal dysplasia inlcude__
- multicystic dysplasia
- aplastic dysplasia
- hypoplastic dysplasia
- obstructive dysplasia
- diffuse dysplasia
Dysplastic kidneys can be large or small. Kidneys with multicystic dysplasia are usually __
Most common cause of abdominal mass lesion in neonates (1 in 5,000 live births) is ___
unilateral renal multicystic dysplasia
Multicystic dysplasia is __ bilateral
- multicystic dysplasia is rarely bilateral and usually NOT part of syndromic anomalies


- diffuse dysplasia is usually bilateral and often occurs as part of a syndrome of congenital anomalies
aplastic renal dysplasia results in a ___
tiny rudimentary dysplastic kidney(s)
- small irregular nondescript islands of tissue in the retroperitoneal fat
unilateral multicystic dysplasia may undergo involution overtime
- distinction from aplastic dysplasia may not be possible in an adult without knowledge of the size of involved kidney during infancy
Kidneys with multicystic dysplasia have a __ shape
irregular, cystic shape
- lack the reniform shape
- variably sized cysts


diffuse dysplasia
- maintains a reniform shape
with relatively uniform sized cysts throughtout BOTH kidneys
hypoplastic dysplasia results in __
- small, mishapen kidneys with multiple conspicuous cysts like multicystic dysplasia, but they are small rather than large
Histologic hallmark of renal dysplasia
- primitive tubules and ducts lined by cuboidal or columnar epithelium, surrounded by poorly differentiated mesenchymal tissue
- may see scattered foci of heterotopic tissue (cartilage, adipose, smooth muscle)

- cartilage is most often found in subcapsular area
obstructive dysplasia is by definition associated with __
congenital urinary tract obstruction
- often see hydronephrosis and bladder hypertrophy
Glomerular epithelial hyperplasia, often seen with ___ dysplasia, should not be confused with ___
- obstructive dysplasia
- not be confused with crescentic glomerulonephritis!! with crescent formation
Diffuse cytsic dysplasia must be distinguished from __
- autosomal recessive polycystic kidney disease
(radially oriented cysts versus the randomly oriented, more rounded cysts of diffuse cystic dysplasia)
- early-onset autosomal dominant PKD

Finding primitive mesenchyme and undifferentiated tubules between the cysts indicates dysplasia!
Renal dysplasias result from abnormal ___
metanephric differentiation
- genetic basis is variable
multicystic dysplasia is __ familial
- rarely familial!!
- probably not a genetic abnormality in most cases

- aplastic and diffuse dysplasia are more often hereditary
Most cases of multicystic and obstructive renal dysplasia are probably due to __
- abnomralities in ureteric bud, ureters, and distal urinary tract
- rather than intrinsic abn of the metanephric blastema
- severe bilateral renal dysplasia
- unilateral renal dysplasia
- bilateral obstructive or hypoplastic dysplasia
- diffuse cystic dysplasia
- severe bilateral renal dysplasia
-- usually lethal due to pulmonary hypoplasia4
- unilateral renal dysplasia
-- may be asymptomatic
- bilateral obstructive or hypoplastic dysplasia
-- often with renal insufficiency and may progress to secondary hydroneprhosis and pyleonephritis
- diffuse cystic dysplasia
-- often a/w with other anomalies as well, which also influence the px
- large unilateral multicystic dysplastic kidney
-- may cause discomfort due to hemorrhage, infarction, or inflammation
Autosomal dominant polycystic kidney disease (ADPKD)
- prevalence
- responsible for __ % of ESRD in USA
- ___ leading cause of ESRD following ___ and___
- 1 in 200-1000 population
- 10%
- third leadind cause of ESRD following diabetes and HTN
ADPKD symptoms usually develop by the ___ decade
third to fourth decade
- 50% have ESRD by age 60

- however, can present at any age or may remain

- patients develop HTN, bilateral flank or abd masses, sense of fullness, hematuria (including blood clots in urine), progressive renal failure
ADPKD that presents in the first year of life usually leads to ___ in childhood
Extrarenal manifestations of ADPKD inlcude:
- cysts in liver, pancreas, spleen, meninges, seminal vesicles
- noncystic manifestations include :
- intracranial aneurysms (10%)
- mitral valve prolapse (20%)
- aortic root dilatation (uncommon)
- dissection of the thoracic aorta (uncommon)
Hepatic cysts a/w ADPKD are usually __
Renal cysts in ADPKD are usually:
- filled with clear or yellow fluid (unless hemorrhagic)
- range 0.5 to 5.0 cm
- contents may be under pressure!!
- cysts present in cortex and medulla
There is an increased risk for __ in ADPKD
Cysts in ADPKD are usually lined by __
- simple cuboidal to columnar to flat epithelium
- scattered areas of epithelial proliferation with multilayering and possibly polypoid projections are often seen
-- RCC can develop in these areas of hyperplasia
As the cysts of ADPKD progressive and increase in size and number they ___
compress and eventually replace the normal renal parenchyma
Glomerular cysts can be seen in ADPKD
- DDX glomerulocystic disease
The histologic picture of ADPKD
- multiple cysts
- atrophic changes
- chronic inflammation
- fibrosis
- hemosiderin pigment
- may see evidence of acute and chronic pyelonephritis
ADPKD versus multiple, simple renal cysts
- simple cysts are common acquired lesions
- usually in outer cortex, bulging the capsule
- lined by nondescript flat epithelium
- extreme expression of this is the acquired cysts a/w with ESRD maintained with chronic dialysis
- clinical context!!

- usually pts dialyzed for 5+ years or develop in end-stage kidneys that remain in transplant recipients
- kidneys are usually smaller (200g) than those of ADPKD (2-4 kg)
Cysts arise from ___ in ADPKD versus only the __ in ARPKD
ADPKD: arise from any part of the nephron, including the glomerulus (glomerular cysts)

ARPKD: arise only from the collecting ducts (no glomerular cysts)

This is important in the DDX of cystic renal disease in children
DDX of a kidney with numerous cysts affecting multiple sites along the neprhon
- tuberous sclerosis
- VHL syndrome
Acquired cystic kidney disease increases risk of RCC. T or F
- as with ADPKD, foci of epithelial hyperplasia may predispose to the formation of RCC
ADPKD is usually inherited as an ___ trait
autosomal dominant trait, but may arise as a spontaneous mutation
85% (majority) of ADPKD is due to genetic abnormality in the ___ gene
- PKD1 gene on chr 16
- PKD2 gene on chr 4 and PKD3 gene (15%)

- code for polycystin-1, polycystin-2, and polycystin-3, respectively
Delayed in onset of symptoms in ADPKD may due to requirement of a
- second hit (acquired disruption of the second allele before the germline mutation can lead to cyst formation in the kidneys or liver)
ADPKD is a progressive disease
- renal cysts increase in size and number with progressive loss of renal parenchyma
Complications of ADPKD
- bacterial pyelo (cyst provide a safe haven)
- most important extrarenal: intracranial arterial anuerysms
ADPKD pts have a __-fold increase of rupture of an intracranial arterial anuerysm
ARPKD may present clinically in __
- in utero
- later in childhood
ARPKD is __ common than ADPKD
- Less common ( 1/10,000 to 50,000 live births) versus ( 1/200 to 1,000)
Most infants with ARPKD __
- are stillborn or die in perinatal period due to pulmonary insufficiency secondary to pulm hypoplasia (olighydraminos and enlarged kidneys causing chest compression)
Kidneys in ARPKD (gross)
- markedly enlarged (bilateral and symmetric)
- enlongated cortical cysts, perpendicular to capsule (radial pattern)
- cysts in the medulla are more rounded
Cysts of ARPKD, in infants that survive past the neonatal period, become __
- rounded
- can make the DDX between ARPDK and early onset ADPKD more challenging
- ADPKD: see glomerular cysts and cysts arising along the nephron in multiple sites
Almost all patients with ARPKD have some degree of __ in the liver
- hepatic biliary dysgenesis (developmental arrest in bile duct formation)
- dilated bile ducts surrounded by fibrosis
- portal areas with expanded interconnecting bile ducts surrounded by fibrous tissue
ARPKD: reciprocal relationship between severity of renal cystic disease and severity of hepatic fibrosis and survival
- short survival (not beyond perinatal period)
-- renal cysts in 90% collecting ducts
-- mild hepatic fibrosis

- survive several months
-- cysts in about 50% collecting ducts
-- mild hepatic fibrosis

- minority of pts who survive longer than a few years
-- cysts in less than 25% of collecting ducts
-- moderate to severe hepatic fibrosis
ARPKD is due to mutation in ___
PKHD1 gene on chr 6
- codes for fibrocystin


ADPKD: PKD1 gene on chr 16, PDK2 gene on chr 4, and PDK3 gene (polycystin-1,2,3)
Primary glomerulocystic diesease
- dx of exclusion: exclude the numerous other cystic disease that can have glomerular cysts as one component

- ADPKD (esp. early-onset)
- renal dysplasia (esp. syndromic diffuse cystic dysplasia and osbructive dysplasia)
- nephronophthisis-medullary cystic disease
nephronophthisis-medullary cystic disease is a group of familial chronic tubulointersitial renal diseases; cysts predominate at the ___
- corticomedullary junction

This is a group of progressive renal disorders that usually have their onset in childhood. The common characteristic is the presence of a variable number of cysts in the medulla, usually concentrated at the corticomedullary junction. Initial injury likely involves the distal tubules with tubular basement membrane disruption, followed by chronic and progressive tubular atrophy involving both medulla and cortex and interstitial fibrosis. Although the presence of medullary cysts is important, the cortical tubulointerstitial damage is the cause ofthe eventual renal insufficiency, and some prefer the term hereditary tubulointerstitial nephritis for this group.[
Nephronophthisis is ___ while medullary cystic disease is ___
Nephronophthisis: autosomal rescessive with early-onset renal failure

Medullary cystic disease is autosomal dominant, with late-onset renal failure

They are grouped together due to overlapping pathologic and clinical features

Patients with MCD often do not present until renal failure is present - histologically there will be cysts involving the medullary pyramids with no/little involvement of the cortex which shows evidence of atrophy

Four variants of this disease complex are recognized: (1) sporadic, nonfamilial (20%); (2) familial juvenile nephronophthisis (40–50%), inherited as an autosomal recessive disease; (3) renal-retinal dysplasia (15%), also an autosomal recessive disease, in which the kidney disease is accompanied by ocular lesions; and (4) adult-onset medullary cystic disease (15%), which shows an autosomal dominant inheritance.

As a group, this complex is now thought to be the most common genetic cause of end-stage renal disease in children and young adults.

Four variants of this disease complex are recognized: (1) sporadic, nonfamilial (20%); (2) familial juvenile nephronophthisis (40–50%), inherited as an autosomal recessive disease; (3) renal-retinal dysplasia (15%), also an autosomal recessive disease, in which the kidney disease is accompanied by ocular lesions; and (4) adult-onset medullary cystic disease (15%), which shows an autosomal dominant inheritance. As a group, this complex is now thought to be the most common genetic cause of end-stage renal disease in children and young adults.

Four variants of this disease complex are recognized: (1) sporadic, nonfamilial (20%); (2) familial juvenile nephronophthisis (40–50%), inherited as an autosomal recessive disease; (3) renal-retinal dysplasia (15%), also an autosomal recessive disease, in which the kidney disease is accompanied by ocular lesions; and (4) adult-onset medullary cystic disease (15%), which shows an autosomal dominant inheritance. As a group, this complex is now thought to be the most common genetic cause of end-stage renal disease in children and young adults.

The expected course is progression to terminal renal failure during a period of 5 to 10 years.
(contrast with medullary sponge kidney, which is a common often asymptomatic lesion, in adults)
Nephronophthisis is associated with extrarenal manifestations, while medullary cystic disease is __
- MCD is NOT!

Nephronophthisis is a/w
- retinitis pigmentosa (Senior-Loken syndrome)
- hepatic fibrosis
- skeletal defects
- cerbellar vermis aplasia
Retinitis pigmentosa
RP is typically thought of as a rod-cone dystrophy in which the genetic defects cause cell death (apoptosis), predominantly in the rod photoreceptors; less commonly, the genetic defects affect the RPE and cone photoreceptors. The phenotypic variation is very significant because over 100 genes can cause RP.

Histopathologic changes in RP have been well documented, and, more recently, specific histologic changes associated with certain gene mutations are being reported. The final common pathway remains photoreceptor cell death by apoptosis. The first histologic change found in the photoreceptors is shortening of the rod outer segments. The outer segments progressively shorten, followed by loss of the rod photoreceptor. This occurs most significantly in the mid periphery of the retina. These regions of the retina reflect the cell apoptosis by having decreased nuclei in the outer nuclear layer. In many cases, the degeneration tends to be worse in the inferior retina, thereby suggesting a role for light exposure.

The final common pathway in RP is typically death of the rod photoreceptors that leads to vision loss. As rods are most densely found in the midperipheral retina, cell loss in this area tends to lead to peripheral vision loss and night vision loss. How a gene mutation leads to slow progressive rod photoreceptor death can occur by many paths, as illustrated by the fact that over 100 gene mutations can lead to a similar clinical picture.

Cone photoreceptor death occurs in a similar manner to rod apoptosis with shortening of the outer segments followed by cell loss. This can occur early or late in the various forms of RP.
Nephronophthsis-medullary cystic disease - gross
- kidneys are normal to small
- advanced disease leads to small fibrotic kidneys
- 75% have 0.1 to 1.5 cm cysts mostly at the corticomedullary junction
- may NOT see cysts (not required for dx)
DDX of prominent medullary cysts
Nephronophthsis-medullary cystic disease
- cysts mostly at the corticomedullary junction (not at papillary tips)
- no calcifications

Medullary sponge kidney
- cysts at the papillary tips
- calcifications involving the cysts
Nephronophthsis-medullary cystic disease involves defects in the ___ tubules
distal tubules
Location of defect:


Nephronophthsis-medullary cystic disease

Medullary sponge kidney
ADPKD: any site along nephron

ARPKD: collecting ducts

Nephronophthsis-medullary cystic disease: distal tubules

Medullary sponge kidney: terminal collecting ducts in medullary pyramids
Medullary sponge kidney is __
congenital dilation of the terminal collecting ducts in the medullary pyramids
Medullary sponge kidney is often__, so the true prevalence is __
- asymptomatic
- unknown
complications of medullary sponge kidney can include
- nephrolithiasis
- infection
- hematuria

in the absence of complications there is a only mild concentrating and acification defects
Kidneys in medullary sponge kidney are __ (gross)
- usually normal size
- 0.1 to 0.8 cm cysts in the medullary pyramids, most numerous in papillary tips

- unilateral or bilateral
- can affect few or most pyramids within a kidney

- irregular calculi and/or blood clot can be found within cysts
most cases of medullary sponge kidney are ___
The DDX for kidneys with cysts arising in multiple sites along the nephrone (glomerular cysts and tubular cysts) should include___
- tuberous sclerosis!!
- Note: there is a possibilty of coexisting ADPKD and TS
Genes involved in tuberous sclerosis
- TSC1 gene: chr 9, hamartin
- TSC2 gene: chr 16, tuberin

NOTE: the genes TSC2 (TS)and PKD1 (ADPKD) are adjacent to one another on chr 16

large mutations that disrupt both genes can lead to concurrent TS and severe early-onset ADPKD
Von Hippel-Lindau syndrome is characterized by
- hemangioblastoma of the CNS
- retinal angiomatosis
- renal cysts
- pancreatic cysts
- pheochromocytoma
VHL: more than half of the patients have renal cysts
renal cysts:
- mutiple, bilateral, up to 5 cm
- scattered throughout kidneys
- cysts wall usually thin, can have epithelial hyperplasia with intracystic excrscences
- can have cystic RCC
RCC a/w VHL is more often
- multiple and bilateral and cystic
Presence of multiple renal cysts with RCC points to a dx of __
- acquired cystic disease a/w dialysis is another multiple cystic disease with RCC
VHL is due to mutation in __
- VHL gene on chr 3
- tumor suppressor gene