renal cystic lesions Flashcards
What is the composition of a simple cortical cyst? Where do they arise from?
Fibrous tissue lined by flattened cuboidal epithelium containing clear serous fluid
Distal convoluted tubule or collecting duct
When measuring cortical cyst wall thickness, what portion of the wall is measured?
The exophytic portion, as the parenchymal portion can be confused with the renal parenchyma
On radionucleotide scans, what feature distinguishes the photopenic cystic lesion from frank hydronephrosis
With a cystic mass lesion, the agent will still fill into the ureter
What are the most common clinical manifestations of cyst rupture
hematuria and flank pain
What is segmental cystic disease of the kidney?
Replacement of all/most of one kidney by multiple cysts
What features make a septation benign of malignant?
Benign - thin, smooth, no nodularity
Malignant - thick, nodular solid mass component
What findings make a cyst complicated?
Septations (thicker/nodular are worse)
Thick wall
Hyperdensity
Enhancement
What is the main difference between hyperdense cyst and renal carcinoma?
Both may look like well defined homogenous hyperdense lesions, but cysts will not enhance
What is pseudoenhancement? What is the problem solving technique?
spurious increase in enhancement after contrast administration caused by the reconstruction algorithm used by modern scanners to adjust for beam hardening effects.
Most pronounced during the early phases of enhancement
Can be reevaluated with alternate imaging modality such as US
What is a Bosniak class I lesion
simple cyst with no atypical features
What is a Bosniak class II lesion
some atypical features though likely benign
thin nonenhancing septa or rimlike calcification
nonehancing hyperdense lesions (hemorrhagic, proteinacious)
What is a bosniak class IIF lesion
minimally complex with suspicious features
increased septa with minimally thickened septa +/- calcifications
hyperdense cysts >3cm that is >75% intrarenal
What is a bosniak class III lesion
Complex
complex septations
multiloculated cysts, thickened walls, dense calcifications, minimal enhancement
What is a bosniak class IV lesion
likely malignant
solid mass with cystic or necrotic component
enhancing solid component or thick irregular walls
What is a milk of calcium cyst? Where are they seen?
Collection of small calcific granules in the cystic fluid (CaCO3) in suspension and layered in the dependent portion.
Seen in the calyceal diverticulum
What are the extrarenal associations with medullary cystic disease in the juvenile population “juvenile nephronophthisis”
retinal degeneration
hepatic fibrosis
skeletal abnormalities
Where are the cysts in medullary cystic disease
medulla, up to 2cm in diameter
cortex is thinned but does not contain cysts
How are the uremic medullary cystic diseases classified?
By age
adult - auto dom MCD
kids - juvenile nephronophthisis
What are the clinical signs associated with auto dom medullary cystic disease
severe anemia with progressive renal failure
salt wasting nephropathy not correct with mineralocorticoids
fixed low specific gravity on UA
HTN late
What is the clinical course of juvenile nephronophthisis
Onset at 3-5 years
anemia and progressive renal failure, more indolent than the adult version
What are the imaging features in medullary cystic disease
US - loss of corticomedullary differentiation, hypoechoic parenchyma compared to liver/spleen
What is the worrisome association with ARPKD
hepatic fibrosis progressing to portal HTN and esophageal varices
Where is the chromosome for ARPKD
6
What is the relationship between hepatic and renal manifestations of ARPKD
inverse; if renal failure, hepatic fibrosis is mild and vice versa
Renal manifestations are seen in the younger patients
Hepatic manifestations are more prominent in the older children
What are the radiologic manifestations of neonatal ARPKD
massive enlargement of the kidneys with maintanence of the reniform shape. Poor renal function is noted clinically
Blotchy opacification on the nephrogram phase with linear striations due to contrast stasis in dilated renal tubules
Small cysts in cortex and medulla cause increased echogenicity on US
Prominent renal pelvis and calyces may results in sonolucent central zone
What are the radiologic manifestations of juvenile ARPKD
Congenital hepatic fibrosis
mildly enlarged but variably sized cysts predominantly medullary in location
increased echogenicity with loss of normal corticomedullary junction
Where are the chromosomes for the two types of ADPKD? Which is more common?
type I - more common, 16
type II - less common, 4
What is the relation between age of onset and severity in ADPKD? What is the expressivity vs penetrance?
What are the associated nonrenal findings?
Later age (>50) better prognosis
100% penetrance
variable expressivity
Saccular berry aneurysms in circle of willis!!!!!
hepatic cysts
mitral valve prolapse
colonic diverticulosis
What is the feared complication with ADPKD?
RCC
What are the CT findings in ADPKD?
innumerable irregularly shaped cysts varying from simple to hemorrhagic to infected
hepatic cysts
Where is the pathology in glomerulocystic disease?
dilation of bowmans space leads to multiple minute cysts, smaller than those in ADPKD
What is multicystic dysplastic kidney? What is the pathophysiology? who get unilateral/bilateral?
Collection of irregularly sized cysts and fibrous tissue without functioning renal parenchyma.
Atresia of the ipsilateral renal vessels with small/absent renal collecting system
Occlusion of the fetal ureters at 8-10 weeks gestation
Uni - male
Bilateral - female
What is the most common abdominal mass in a neonate? second most?
Hydronephrosis
Multicystic dysplastic kidney
What are the renal associations with multicystic dysplastic kidney?
UPJ obstruction
hypoplasia of opposite kidney
horseshoe kidney
What are the 3 main findings in multicystic dysplastic kidney?
Irregular mass of dysplastic cystic tissue
No renal artery
Absent collecting system and atretic/absent ureter
What are the CXR findings of multicystic dysplastic kidney? CT? US?
soft tissue flank mass with cystic wall calcification
compensatory hypertrophy of the contralateral kidney
multiple cysts with thick septa and mural calcifications (CT)
who gets segmental multicystic renal dysplasia
partial obstruction in utero with an ectopic ureterocele
What is the difference between classic and hydronephrotic multicystic dysplastic kidney? Why is it important
Hydronephrotic subtype has communication between the cysts and pelvis
Hydronephrosis can have surgery to preserve renal function
What is multilocular cystic nephroma
well circumscribed lesion containing many cysts of variable sizes
surrounded by a thick fibrous capsule that compresses adjacent renal parenchyma and often projects into the renal pelvis
What is the age difference in multiloculated cystic nephroma?
Males 40yo
What are the US and CT findings in multilocular cystic nephroma
US - large lesion with multiple locules separated by echogenic stroma
CT - 10cm lesion sharply delineated from adjacent renal parenchyma. Lesion doesnt enhance, but septations will
HERNIATION OF MASS INTO PELVIS
What are the renal findings in tuberous sclerosis?
Zits, fits, and nitwits
80% have AML
increased incidence of cysts, usually
What are the findings in VHL? What are the three types?
Cerebellar and retinal hemangioblastoma RCC Renal cysts Pancreatic islet cell tumors and cysts Pheochromocytoma
Type I - retinal/CNS hemangioblastoma, renal cyst/RCC, pancreatic cystic disease
Type IIA - retinal/CNS hemangioblastoma, pheochromocytoma, pancreatic islet cells tumors, NO RENAL DISEASE
Type IIB - Type I + pheochromocytoma
What is the pathophysiology behind cyst development in dialysis?
Incomplete removal of toxins induces fusiform dilations of proximal renal tubules
What is the risk of malignancy in dialysis patients?
3-6x general population
After renal transplant, what happens to the cysts and cancers in dialysis patients?
Cysts tend to regress
Still slight increased risk of cancer
What is acquired renal cystic disease? What are the renal findings
Seen after longterm dialysis
multiple cysts in small/normal kidneys
increased risk of renal cancer
dystrophic calcification
What is renal lymphangiomatosis>?
presence of multiple cysts in both the renal sinus and renal parenchyma
What are the renal findings in orofaciodigital syndrome?
multiple renal cysts with development of renal insufficiency
What are the features of a hydatid cyst that separate it from a simple cyst?
curvilinear calcification of the wall, septations, scolex/daughter component
What is a pyelogenic cyst?
cyst that communicates with the collecting system through and narrow isthmus
The connection is at the fornix but can be at any portion of the calyx
What is the difference in contrast filling between a calyceal diverticulum and hydronephrosis?
The normal calyces will fill in before the diverticulum, whereas hydronephrosis will fill in the large cystic portion first
What is the difference between parapelvic and peripelvic cysts
Para - renal sinus cyst
Peri - multiple lymphatic dilations
How can you tell the difference between renal pelvic lipomatosis and parapelvic cysts?
Lipomatosis will have fat attenuation/echogenicity
What is a perinephric cyst?
Not a true cyst, thought to be due to collection of urine after trauma
Located under the renal capsule
