Cystic Renal Disease

Cystic Renal Cystic Renal DiseaseDiseaseJud Gash, MDJud Gash, MD

Cystic Renal DiseaseCystic Renal Disease

OverviewOverview Simple CystSimple Cyst

complicatedcomplicated hyperdensehyperdense Bosniak classificationBosniak classification

Cysts and cancerCysts and cancer ACKD, TS & VHLACKD, TS & VHL

Multicystic dysplastic kidneysMulticystic dysplastic kidneys Autosomal Dominant and Recessive PolycysticAutosomal Dominant and Recessive Polycystic Medullary Sponge KidneyMedullary Sponge Kidney Medullary Cystic DiseaseMedullary Cystic Disease Localized Cystic Renal DiseaseLocalized Cystic Renal Disease Renal Sinus CystsRenal Sinus Cysts

Simple CystSimple Cyst Most common adult renal mass (50% > Most common adult renal mass (50% >

50yo)50yo) Cortical; straw colored fluidCortical; straw colored fluid usually asymptomaticusually asymptomatic BIB themBIB them

Simple CystSimple Cyst IVP (historical)IVP (historical)

homogeneous, homogeneous, lucentlucent

thin walls, smooth thin walls, smooth interfaceinterface

““beak signbeak sign”” - implies - implies indolent processindolent process

Cannot dx on IVP; Cannot dx on IVP; must confirm (US must confirm (US or CT)or CT)

Simple CystSimple Cyst UltrasoundUltrasound

anechoicanechoic thin, smooth wallthin, smooth wall increased thru increased thru

transmissiontransmission

Simple CystSimple Cyst CT and MRICT and MRI

near water density (< near water density (< 10 HU)10 HU)

Check HUCheck HU’’s of other s of other waterwater

thin, smooth wallthin, smooth wall homogeneoushomogeneous No enhancementNo enhancement MRI>CTMRI>CT Veritas tip – test Veritas tip – test

yourself before ROIyourself before ROI Pitfall – beware of Pitfall – beware of

Papillary RCCPapillary RCC

Simple CystSimple Cyst

Too small to characterize Too small to characterize (subcentimeter) renal hypodensity(subcentimeter) renal hypodensity 2 points:2 points:

OK to say very likely cyst and BIB itOK to say very likely cyst and BIB it Although cant get water HUAlthough cant get water HU’’ss

A 5 mm cyst is more hypodense to your eye than A 5 mm cyst is more hypodense to your eye than 5 mm solid lesion5 mm solid lesion

Cyst-makers vs StrandersCyst-makers vs Stranders

Complicated Renal CystComplicated Renal Cyst

Simple cysts may become infected or Simple cysts may become infected or hemorrhage/traumahemorrhage/trauma

US/CT/MRI US/CT/MRI Thick walls; calcifications, septations, debris Thick walls; calcifications, septations, debris

or increased attenuationor increased attenuation And so, overlaps the appearance of cystic RCCAnd so, overlaps the appearance of cystic RCC

And therefore Bosniak ClassificationAnd therefore Bosniak Classification

56 y/o with renal 56 y/o with renal massmass

Hemorrhagic cyst at surgery

74 with flank pain74 with flank pain

Hyperdense CystHyperdense Cyst Benign cyst containing blood products Benign cyst containing blood products

(clotted, old - not just acute)(clotted, old - not just acute) 50 -90 HU (hyperdense to water or kidney)50 -90 HU (hyperdense to water or kidney)

if no NCCT, can be isodense or hypodense to kidney if no NCCT, can be isodense or hypodense to kidney on CCTon CCT

USUS 50% appear cystic( a few echoes), but may not50% appear cystic( a few echoes), but may not

CT CriteriaCT Criteria < 3cm< 3cm smooth wall (must extend beyond margin to evaluate)smooth wall (must extend beyond margin to evaluate) rounded; sharp marginsrounded; sharp margins **** **** NO SIGNIFICANT ENHANCEMENTNO SIGNIFICANT ENHANCEMENT **** ****

Hyperdense CystHyperdense Cyst



Must distinguish from Must distinguish from RCCRCC

if strict CT criteria or US, if strict CT criteria or US, then some stop (II) or then some stop (II) or some follow (IIF)some follow (IIF)

if comes very close if comes very close (intrarenal, 3.5 cm, (intrarenal, 3.5 cm, elderly) could follow (IIF)elderly) could follow (IIF)

if doesnt meet criteria, if doesnt meet criteria, ““cannot RO RCCcannot RO RCC””

New Data helpful TooNew Data helpful Too >70HU noncontrast>70HU noncontrast

Bosniak ClassificationBosniak Classification

Most problematic renal masses are cysticMost problematic renal masses are cystic Bosniak created a classification scheme Bosniak created a classification scheme

to guide proper managementto guide proper management ClassificationClassification

I - simple cystI - simple cyst II - minimally complicated (1 or 2 thin, II - minimally complicated (1 or 2 thin,

““nonenhancingnonenhancing””septi, delicate Ca++ in septi or septi, delicate Ca++ in septi or wall; hyperdense)wall; hyperdense)

III - thick walls or Ca++, thick septi, nodulesIII - thick walls or Ca++, thick septi, nodules IV - definitely malignant (necrotic masses, etc.)IV - definitely malignant (necrotic masses, etc.)

Bosniak IBosniak I

Bosniak IIBosniak II

Bosniak II-FBosniak II-F

Bosniak IIIBosniak III

Bosniak IVBosniak IV

Bosniak ClassificationBosniak Classification

ManagementManagement I - stopI - stop II - stop or follow Up (IIf)II - stop or follow Up (IIf) III & IV - surgeryIII & IV - surgery

Although most III will be benign, 30% will be Although most III will be benign, 30% will be cancercancer

ProblemsProblems Category II lesions (at least one study Category II lesions (at least one study

showed 4/5 malignant)showed 4/5 malignant) Interobserver variability between II and IIIInterobserver variability between II and III

Cysts and CancerCysts and Cancer

3 main areas3 main areas Acquired cystic kidney disease (ACKD)Acquired cystic kidney disease (ACKD) Tuberous Sclerosis (TS)Tuberous Sclerosis (TS) Von-Hipple Lindau (VHL)Von-Hipple Lindau (VHL)

Acquired Cystic Renal Acquired Cystic Renal DiseaseDisease

Development of cysts and occasional Development of cysts and occasional neoplasms in patients with CRFneoplasms in patients with CRF

Can occur without dialysis (10%) but very Can occur without dialysis (10%) but very common in patients with dialysis (either common in patients with dialysis (either hemo or peritoneal)hemo or peritoneal)

? prolongs lifespan so cysts develop? prolongs lifespan so cysts develop 50% at 5 yrs, 90% at 10 years50% at 5 yrs, 90% at 10 years

Impact of transplantImpact of transplant controversialcontroversial cysts - some regress, some dontcysts - some regress, some dont neoplasms - again controversialneoplasms - again controversial

Acquired Cystic Renal Acquired Cystic Renal DiseaseDisease

FindingsFindings CystsCysts

small early; small early; enlarge and enlarge and multiply in time; multiply in time; can mimic can mimic ADPCKDADPCKD

commonly Ca++, commonly Ca++, hemorrhagehemorrhage

NeoplasmsNeoplasms definite increased definite increased

risk with CRF, risk with CRF, again esp. dialysisagain esp. dialysis

often indolent in often indolent in nature (papillary nature (papillary RCC)RCC)

kidneys small; kidneys small; atrophic; atrophic; hyperechoic; no hyperechoic; no other cystsother cysts

Tuberous SclerosisTuberous Sclerosis Renal manifestations occur Renal manifestations occur

in majority in majority Cysts – 15-50%Cysts – 15-50%

When occur tend to be in young When occur tend to be in young childrenchildren

AMLAML’’s – 80%s – 80% Neoplasm (RCC) Neoplasm (RCC)

Controversial whether increased Controversial whether increased incidenceincidence

predisposition suggested by predisposition suggested by younger age and bilateral natureyounger age and bilateral nature

No extrarenal cystsNo extrarenal cysts

Renal cysts in a 10-month-old with TS.

Von Hippel-LindauVon Hippel-Lindau

Renal Renal manifestations manifestations also commonalso common

FindingsFindings Cysts – 50-75%Cysts – 50-75%

BL; MulitpleBL; Mulitple RCC - 35% RCC - 35%

bl and multiplebl and multiple Aggressive Aggressive

behaviorbehavior pancreatic cystspancreatic cysts

Multicystic Dysplastic Multicystic Dysplastic KidneyKidney

Congenital, non-hereditary dysplasia Congenital, non-hereditary dysplasia characterized by renal parenchyma characterized by renal parenchyma replaced by multiple cystsreplaced by multiple cysts

due to dysplastic ureteral buddue to dysplastic ureteral bud ClinicalClinical

May present as abdominal mass in child or May present as abdominal mass in child or incidental in adultincidental in adult

** 10-30% incidence of contralateral ** 10-30% incidence of contralateral anomaly, esp UPJ and reflux**anomaly, esp UPJ and reflux**


TypesTypes pelvoinfundibular pelvoinfundibular

atresia (most atresia (most common) - atretic common) - atretic renal pelvis and renal pelvis and ureter; cystic renal ureter; cystic renal massmass

Hydronephrotic Hydronephrotic type (rare) - ureteral type (rare) - ureteral atresia but dilated atresia but dilated pelvispelvis

segmental (rare) - in segmental (rare) - in duplicated systemduplicated system


FindingsFindings No functionNo function multiple noncommunicating cysts replacing multiple noncommunicating cysts replacing

kidneykidney Usually no large central cystic area (UPJ)Usually no large central cystic area (UPJ) large in childlarge in child Small to large, often Ca++ in adult (fails to Small to large, often Ca++ in adult (fails to

grow)grow) MUST evaluate contra-lateral sideMUST evaluate contra-lateral side

Mercado-Deane M et al. Radiographics 2002;22:1429-1438



Huppert B J et al. Radiographics 1999;19:S215-S227

23 week fetus with MCDK

Autosomal Dominant Autosomal Dominant Polycystic Kidney Polycystic Kidney

DiseaseDisease ClinicallyClinically

May present prenatally to elderlyMay present prenatally to elderly Classically presents with CRF in 30-40 yoClassically presents with CRF in 30-40 yo ProblemsProblems

Renal Failure - often, but not always, Renal Failure - often, but not always, progressiveprogressive

HTN, UTIHTN, UTI’’s and pains and pain SAH SAH

Autosomal Dominant conditionAutosomal Dominant condition


DiseaseDisease ManifestationManifestation

Renal CystsRenal Cysts start small but enlarge over timestart small but enlarge over time enlarge the kidneyenlarge the kidney often complicated with Ca++, hemorrhageoften complicated with Ca++, hemorrhage usually bl, symetric involvementusually bl, symetric involvement

Extrarenal cystsExtrarenal cysts liver (40-90%)liver (40-90%) pancreas (10%)pancreas (10%) Spleen (5%)Spleen (5%)

Cerebral aneurysms (15-40%)Cerebral aneurysms (15-40%) No increased risk of RCCNo increased risk of RCC


DiseaseDisease IVPIVP

Bilateral enlarged lobulated kidneysBilateral enlarged lobulated kidneys swiss cheese nephrogram (multiple swiss cheese nephrogram (multiple

lucencies on nephrogram) lucencies on nephrogram) arachnoid calyces (elongated, stretched arachnoid calyces (elongated, stretched

calyces)calyces)

US & CT/MRIUS & CT/MRI bilateral large kidneys with cystsbilateral large kidneys with cysts

often with Ca++, hyperdenseoften with Ca++, hyperdense Extrarenal cystsExtrarenal cysts

Autosomal Dominant Autosomal Dominant Polycystic Kidney DiseasePolycystic Kidney Disease

Autosomal Dominant Autosomal Dominant Polycystic Kidney DiseasePolycystic Kidney Disease

Autosomal Recessive Autosomal Recessive Polycystic Kidney Polycystic Kidney

DiseaseDisease Genetic condition two primary Genetic condition two primary

abnormalitiesabnormalities Kidneys - cystic dilatation (1-8mm) of the Kidneys - cystic dilatation (1-8mm) of the

collecting ducts -> renal failurecollecting ducts -> renal failure Biliary - biliary ectasia/periportal fibrosis -> Biliary - biliary ectasia/periportal fibrosis ->

portal hypertension; liver failureportal hypertension; liver failure


DiseaseDisease ClinicallyClinically

Classically classified as perinatal, neonatal, Classically classified as perinatal, neonatal, infantile and juvenile; now felt to be too infantile and juvenile; now felt to be too rigidrigid

Spectrum of expression with predominately Spectrum of expression with predominately renal and minimal hepatic disease when renal and minimal hepatic disease when presentation in perinatal period; and presentation in perinatal period; and predominately hepatic and milder renal predominately hepatic and milder renal disease when presenting in the older childdisease when presenting in the older child

An individual can present anywhere along An individual can present anywhere along the spectrumthe spectrum


DiseaseDisease ImagingImaging Perinatal form (most Perinatal form (most

common)common) massive nephromegaly massive nephromegaly

usually without discrete usually without discrete cysts dominates the cysts dominates the imagingimaging

Prenatal US - enlarged Prenatal US - enlarged hyperechoic kidneys; hyperechoic kidneys; decreased or absent decreased or absent bladder; oligohydramniosbladder; oligohydramnios

PF - flank masses; pulm. PF - flank masses; pulm. hypoplasia with ptxhypoplasia with ptx

US - enlarged echogenic US - enlarged echogenic kidneys with loss of CMJkidneys with loss of CMJ

CT - nehpromegaly; CT - nehpromegaly; striated prolonged striated prolonged nephrogramnephrogram

Liver US - usually normal Liver US - usually normal or slightly hyperechoicor slightly hyperechoic


DiseaseDisease

Autosomal Recessive Autosomal Recessive Polycystic Kidney DiseasePolycystic Kidney Disease


DiseaseDisease ImagingImaging Older childOlder child

The kidneys appear The kidneys appear normal or similar to normal or similar to perinatal findings, perinatal findings, only milder; occ. only milder; occ. discrete cystsdiscrete cysts

Liver US - Liver US - hyperechoic; may hyperechoic; may see cystic dilatation see cystic dilatation of the biliary tree; of the biliary tree; changes of portal changes of portal HTN (HSM; HTN (HSM; varices)varices)

Medullary Sponge Medullary Sponge KidneyKidney

PathologyPathology saccular 1-8mm saccular 1-8mm

dilatation of the distal dilatation of the distal collecting ducts with collecting ducts with sluggish flow and sluggish flow and predisposition to predisposition to stone formationstone formation

ClinicalClinical Young adultsYoung adults usually asymptomatic usually asymptomatic

except stonesexcept stones non-hereditary; non-non-hereditary; non-

progressiveprogressive assoc. with Caroliassoc. with Caroli’’s, s,

ARPCKD; ARPCKD; hemihypertrophyhemihypertrophy


Imaging (PF, US and CT)Imaging (PF, US and CT) Medullary nephrocalcinosisMedullary nephrocalcinosis

bilateral, unilateral or focalbilateral, unilateral or focal ““growing calculus signgrowing calculus sign””

UrolithiasisUrolithiasis Discrete linear collections in papilla on IVPDiscrete linear collections in papilla on IVP

should be distinguished papillary blush - a should be distinguished papillary blush - a nondiscrete blush of contrast within the nondiscrete blush of contrast within the papillary which can be normalpapillary which can be normal





Medullary Cystic DiseaseMedullary Cystic Disease

ClinicopathologicClinicopathologic Rare inherited Rare inherited

diseasedisease Chronic failure in Chronic failure in

early adulthoodearly adulthood Medullary cystsMedullary cysts two typestwo types

ImagingImaging Medullar cystsMedullar cysts small, smooth small, smooth

kidneys with poor kidneys with poor functionfunction

Occasionally see Occasionally see dilated, contrast dilated, contrast filled tubules in filled tubules in medulla (mimics medulla (mimics MSK)MSK)

No ca++No ca++

Localized Cystic DiseaseLocalized Cystic Disease

Multiple Multiple conglomerateconglomerated cysts with d cysts with intervening intervening normal (or normal (or compressed) compressed) renal tissuerenal tissue

Uncommon Uncommon and benignand benign

Unilateral Unilateral (other kidney (other kidney normal)normal)

Part or all of Part or all of kidneykidney

AJR 2001; 176:843-849

Localized Cystic DiseaseLocalized Cystic Disease DDXDDX

AbscessAbscess MCDKMCDK

Kidney functions Kidney functions normallynormally

MLCN and MLCN and CysticRCCCysticRCC

Normal interneving Normal interneving tissue and lack of tissue and lack of capsulecapsule

Should FollowShould Follow Can GrowCan Grow

Multilocular cystic RCC – capsule with enhancing tumorous septa

AJR 2001; 176:843-849

Renal Sinus CystsRenal Sinus Cysts

2 types2 types parapelvic cystparapelvic cyst

simple parenchymal cyst which projects into the simple parenchymal cyst which projects into the sinussinus

peripelvic cystperipelvic cyst extraparenchymal cyst arising in sinus (?origin; ? extraparenchymal cyst arising in sinus (?origin; ?

congenital and lymphatic etiology)congenital and lymphatic etiology)

Imaging (peripelvic)Imaging (peripelvic) May be multiple and bilateral, unilocular or May be multiple and bilateral, unilocular or

multilocular; usually small and insinuatingmultilocular; usually small and insinuating smooth splaying of collecting systemsmooth splaying of collecting system rarely results in obstruction and hydronephrosisrarely results in obstruction and hydronephrosis

Renal Sinus CystRenal Sinus Cyst(parapelvic)(parapelvic)


ImagingImaging USUS

cyst in cyst in renal sinusrenal sinus

CTCT sinus cyst sinus cyst

(delays (delays needed to needed to exclude exclude hydro) hydro)

DDX - DDX - hydronephrosishydronephrosis



Cystic Renal DiseaseCystic Renal Disease

ReviewReview Simple CystSimple Cyst

complicatedcomplicated hyperdensehyperdense Bosniak classificationBosniak classification

Cysts and cancerCysts and cancer ACKD, TS & VHLACKD, TS & VHL

Multicystic dysplastic kidneysMulticystic dysplastic kidneys Autosomal Dominant and Recessive PolycysticAutosomal Dominant and Recessive Polycystic Medullary Sponge KidneyMedullary Sponge Kidney Medullary Cystic DiseaseMedullary Cystic Disease Localized Cystic DiseaseLocalized Cystic Disease Renal Sinus CystsRenal Sinus Cysts

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Cystic Renal Disease