Imaging of cystic renal disease

1. Cystic Renal Disease
Jud Gash, MD

2. Cystic Renal Disease
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Overview
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Simple Cyst
 complicated
 hyperdense
 Bosniak classification
Cysts and cancer
 ACKD, TS & VHL
Multicystic dysplastic kidneys
Autosomal Dominant and Recessive Polycystic
Medullary Sponge Kidney
Medullary Cystic Disease
Localized Cystic Renal Disease
Renal Sinus Cysts

3. Simple Cyst
Most common adult renal mass (50% > 50yo)
 Cortical; straw colored fluid
 usually asymptomatic
 BIB them


4. Simple Cyst

IVP (historical)
homogeneous, lucent
 thin walls, smooth
interface
 “beak sign” - implies
indolent process
 Cannot dx on IVP; must
confirm (US or CT)


5. Simple Cyst
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Ultrasound
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anechoic
thin, smooth wall
increased thru transmission

6. Simple Cyst
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CT and MRI
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near water density (< 10 HU)
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Check HU’s of other water
thin, smooth wall
homogeneous
No enhancement
MRI>CT
Veritas tip – test yourself
before ROI
Pitfall – beware of Papillary
RCC

7. Simple Cyst

Too small to characterize (subcentimeter) renal
hypodensity

2 points:
OK to say very likely cyst and BIB it
 Although cant get water HU’s
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A 5 mm cyst is more hypodense to your eye than 5 mm solid
lesion

8. Cyst-makers vs Stranders

9. Complicated Renal Cyst
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Simple cysts may become infected or
hemorrhage/trauma
US/CT/MRI
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Thick walls; calcifications, septations, debris or increased
attenuation
And so, overlaps the appearance of cystic RCC
 And therefore Bosniak Classification

10. 56 y/o with renal mass
Hemorrhagic cyst
at surgery

11. 74 with flank pain

12. Hyperdense Cyst
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Benign cyst containing blood products (clotted, old not just acute)
50 -90 HU (hyperdense to water or kidney)
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if no NCCT, can be isodense or hypodense to kidney on CCT
50% appear cystic( a few echoes), but may not
US
CT Criteria
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< 3cm
smooth wall (must extend beyond margin to evaluate)
rounded; sharp margins
**** NO SIGNIFICANT ENHANCEMENT ****

13. Hyperdense Cyst

14. Hyperdense Cyst

15. Hyperdense Cyst

Must distinguish from RCC
if strict CT criteria or US, then
some stop (II) or some follow
(IIF)
 if comes very close (intrarenal,
3.5 cm, elderly) could follow
(IIF)
 if doesnt meet criteria, “cannot
RO RCC”
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New Data helpful Too
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>70HU noncontrast

16. Bosniak Classification
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Most problematic renal masses are cystic
Bosniak created a classification scheme to guide
proper management
Classification
I - simple cyst
 II - minimally complicated (1 or 2 thin,
“nonenhancing”septi, delicate Ca++ in septi or wall;
hyperdense)
 III - thick walls or Ca++, thick septi, nodules
 IV - definitely malignant (necrotic masses, etc.)


17. Bosniak I

18. Bosniak II

19. Bosniak II-F

20. Bosniak III

21. Bosniak IV

22. Bosniak Classification

Management
I - stop
 II - stop or follow Up (IIf)
 III & IV - surgery
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Although most III will be benign, 30% will be cancer
Problems
Category II lesions (at least one study showed 4/5
malignant)
 Interobserver variability between II and III
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23. Cysts and Cancer
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3 main areas
Acquired cystic kidney disease (ACKD)
 Tuberous Sclerosis (TS)
 Von-Hipple Lindau (VHL)
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24. Acquired Cystic Renal Disease
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Development of cysts and occasional neoplasms in
patients with CRF
Can occur without dialysis (10%) but very common in
patients with dialysis (either hemo or peritoneal)
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? prolongs lifespan so cysts develop
50% at 5 yrs, 90% at 10 years
Impact of transplant
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controversial
cysts - some regress, some dont
neoplasms - again controversial

25. Acquired Cystic Renal Disease
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Findings
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Cysts
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Neoplasms
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small early; enlarge
and multiply in time;
can mimic ADPCKD
commonly Ca++,
hemorrhage
definite increased risk
with CRF, again esp.
dialysis
often indolent in
nature (papillary RCC)
kidneys small;
atrophic; hyperechoic;
no other cysts

26. Tuberous Sclerosis
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Renal manifestations
occur in majority
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Cysts – 15-50%
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AML’s – 80%
Neoplasm (RCC)
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When occur tend to be in
young children
Controversial whether
increased incidence
predisposition suggested by
younger age and bilateral
nature
No extrarenal cysts
Renal cysts in a 10-month-old with TS.

27. Von Hippel-Lindau
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Renal manifestations
also common
Findings
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Cysts – 50-75%
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RCC - 35%
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BL; Mulitple
bl and multiple
Aggressive behavior
pancreatic cysts

28. Multicystic Dysplastic Kidney
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Congenital, non-hereditary dysplasia
characterized by renal parenchyma replaced by
multiple cysts
due to dysplastic ureteral bud
Clinical
May present as abdominal mass in child or incidental in
adult
 ** 10-30% incidence of contralateral anomaly, esp UPJ
and reflux**


29. Multicystic Dysplastic Kidney

Types
pelvoinfundibular atresia
(most common) - atretic
renal pelvis and ureter;
cystic renal mass
 Hydronephrotic type
(rare) - ureteral atresia
but dilated pelvis
 segmental (rare) - in
duplicated system


30. Multicystic Dysplastic Kidney

Findings
No function
 multiple noncommunicating cysts replacing kidney
 Usually no large central cystic area (UPJ)
 large in child
 Small to large, often Ca++ in adult (fails to grow)
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MUST evaluate contra-lateral side

31. Multicystic Dysplastic Kidney
Mercado-Deane M et al. Radiographics 2002;22:1429-1438

32. Multicystic Dysplastic Kidney

33. 23 week fetus with MCDK
Huppert B J et al. Radiographics 1999;19:S215-S227

34. Autosomal Dominant Polycystic
Kidney Disease
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Clinically
May present prenatally to elderly
 Classically presents with CRF in 30-40 yo
 Problems
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Renal Failure - often, but not always, progressive
HTN, UTI’s and pain
SAH
Autosomal Dominant condition

35. Autosomal Dominant Polycystic
Kidney Disease
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Manifestation
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Renal Cysts
 start small but enlarge over time
 enlarge the kidney
 often complicated with Ca++, hemorrhage
 usually bl, symetric involvement
Extrarenal cysts
 liver (40-90%)
 pancreas (10%)
 Spleen (5%)
Cerebral aneurysms (15-40%)
No increased risk of RCC

36. Autosomal Dominant Polycystic
Kidney Disease

IVP
Bilateral enlarged lobulated kidneys
 swiss cheese nephrogram (multiple lucencies on
nephrogram)
 arachnoid calyces (elongated, stretched calyces)
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US & CT/MRI
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bilateral large kidneys with cysts
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often with Ca++, hyperdense
Extrarenal cysts

37. Autosomal Dominant Polycystic
Kidney Disease

38. Autosomal Dominant Polycystic
Kidney Disease

39. Autosomal Recessive Polycystic
Kidney Disease

Genetic condition two primary abnormalities
Kidneys - cystic dilatation (1-8mm) of the collecting ducts
-> renal failure
 Biliary - biliary ectasia/periportal fibrosis -> portal
hypertension; liver failure


40. Autosomal Recessive Polycystic
Kidney Disease

Clinically
Classically classified as perinatal, neonatal, infantile and
juvenile; now felt to be too rigid
 Spectrum of expression with predominately renal and
minimal hepatic disease when presentation in perinatal
period; and predominately hepatic and milder renal
disease when presenting in the older child
 An individual can present anywhere along the spectrum


41. Autosomal Recessive Polycystic
Kidney Disease
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Imaging
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Perinatal form (most common)
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massive nephromegaly usually
without discrete cysts dominates
the imaging
Prenatal US - enlarged
hyperechoic kidneys; decreased
or absent bladder;
oligohydramnios
PF - flank masses; pulm.
hypoplasia with ptx
US - enlarged echogenic kidneys
with loss of CMJ
CT - nehpromegaly; striated
prolonged nephrogram
Liver US - usually normal or
slightly hyperechoic

42. Autosomal Recessive Polycystic
Kidney Disease

43. Autosomal Recessive Polycystic
Kidney Disease

44. Autosomal Recessive Polycystic
Kidney Disease
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Imaging
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Older child
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The kidneys appear
normal or similar to
perinatal findings, only
milder; occ. discrete cysts
Liver US - hyperechoic;
may see cystic dilatation
of the biliary tree; changes
of portal HTN (HSM;
varices)

45. Medullary Sponge Kidney
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Pathology
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saccular 1-8mm dilatation of
the distal collecting ducts
with sluggish flow and
predisposition to stone
formation
Clinical
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Young adults
usually asymptomatic except
stones
non-hereditary; nonprogressive
assoc. with Caroli’s,
ARPCKD; hemihypertrophy

46. Medullary Sponge Kidney
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Imaging (PF, US and CT)
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Medullary nephrocalcinosis
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bilateral, unilateral or focal
“growing calculus sign”
Urolithiasis
 Discrete linear collections in papilla on IVP
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should be distinguished papillary blush - a nondiscrete blush
of contrast within the papillary which can be normal

47. Medullary Sponge Kidney

48. Medullary Sponge Kidney

49. Medullary Sponge Kidney

50. Medullary Sponge Kidney

51. Medullary Cystic Disease
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Clinicopathologic
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Rare inherited disease
Chronic failure in early
adulthood
Medullary cysts
two types
Imaging
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Medullar cysts
small, smooth kidneys with
poor function
Occasionally see dilated,
contrast filled tubules in
medulla (mimics MSK)
No ca++

52. Localized Cystic Disease
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Multiple
conglomerated
cysts with
intervening
normal (or
compressed) renal
tissue
Uncommon and
benign
Unilateral (other
kidney normal)
Part or all of
kidney
AJR 2001; 176:843-849

53. Localized Cystic Disease
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DDX
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Abscess
MCDK
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MLCN and CysticRCC
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Kidney functions
normally
Normal interneving tissue
and lack of capsule
Should Follow

Can Grow
Multilocular cystic RCC – capsule
with enhancing tumorous septa
AJR 2001; 176:843-849

54. Renal Sinus Cysts
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2 types
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parapelvic cyst
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peripelvic cyst
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simple parenchymal cyst which projects into the sinus
extraparenchymal cyst arising in sinus (?origin; ?
congenital and lymphatic etiology)
Imaging (peripelvic)
May be multiple and bilateral, unilocular or
multilocular; usually small and insinuating
 smooth splaying of collecting system
 rarely results in obstruction and hydronephrosis


55. Renal Sinus Cyst
(parapelvic)

56. Renal Sinus Cysts
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Imaging
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US
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cyst in renal
sinus
sinus cyst
(delays needed
to exclude
hydro)
CT
DDX hydronephrosis

57. Renal Sinus Cysts

58. Renal Sinus Cysts

59. Cystic Renal Disease

Review
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
Simple Cyst
 complicated
 hyperdense
 Bosniak classification
Cysts and cancer
 ACKD, TS & VHL
Multicystic dysplastic kidneys
Autosomal Dominant and Recessive Polycystic
Medullary Sponge Kidney
Medullary Cystic Disease
Localized Cystic Disease
Renal Sinus Cysts