Renal Masses
Robert D. Thomas MD
Pediatric Radiology
Renal Masses
Balls Cyst Hematoma Abscess Tumor Dromedary hump
Beans Duplication/anomaly Compensatory
hypertrophy Hydronephrosis Pyelonephritis/edema Hematoma PCKD Tumor Vascular
occlusion/trauma
Renal Masses by Age
Newborn Hydronephrosis MCDK AR-PCKD Anomalies Tumors
Mesoblastic nephroma
Nephroblastomatosis
Childhood Cysts Hydronephrosis,
MCDK Anomalies Hematoma Tumors
Wilms Lymphoma Angiomyolipomas
Hydronephrosis(Bean) Calyceal/Pelvic obstruction
Congenital (intrinsic/extrinsic) TB Tumor
Ureter Physiologic (full bladder) Congenital (1 megaureter, ectopic ureter,
retrocaval) Inflammatory (TB, Crohn, PID, etc) Intraluminal (stone, clot, tumor, stricture)
Congenital UPJ obstruction
#1 cause of renal mass in newborn Associations
Ipsilateral reflux Lower moiety of duplication Most common cause of obstruction with
horseshoe kidney
Causes Stricture, disordered peristalsis, ischemia,
redundant urothelium, crossing vessel, etc.
Congenital UPJ obstruction
Imaging: Mass in plain films US – dilated pelvo-calyceal system (communicating
cysts): dilatation-fluid equal to cortical thickness NM – obstructive pattern w/o lasix response
Pitfalls US may underestimate hydro due to
oliguria/dehydration in newborn MCDK may look like UPJ if only a couple cysts
present
Congenital UPJ obstruction
Work-up VCUG: co-existant ipsilateral reflux*,
urethral obstruction, contralateral reflux Scintigraphy: site of obstruction & renal
function
*obstruction to reflux at UPJ, dilution of contrast in dilated renal pelvis, delay in drainage from renal pelvis
Multicystic Dysplastic KidneyBean or Ball Not a true “cystic disease” etiology is severe embryonic
obstruction during metanephric stage of development
So…it’s an obstruction Hallmark: non-function of the kidney Bilaterality not compatible with life due
to severe pulmonary hypoplasia
Multicystic Dysplastic Kidney
2nd most common renal mass in newborn Types
Pelvoinfundibular – atresias at ureter, pelvis, infundibulae
Most common, grape-like collection of cysts and dysplastic glomeruli, atrophied tubules
Hydronephrotic-atresia of proximal ureter alone Uncommon (5%)
Multicystic Dysplastic Kidney
Imaging US - Isolated cysts without a definable
pelvis and without normal renal tissue IVP – lack of function NM – absence of perfusion & lack of
function (may have minimal activity 24-48hrs)
Multicystic Dysplastic Kidney
Work-up US: frequent contralateral UPJ, reflux, VCUG: opposite reflux/obstruction MAG3, DTPA renogram
Management Usually observation (natural history of involution) Nephrectomy for GI obstruction/respiratory
compromise, hypertension ?malignancy probably not increased over baseline
Solid Renal MassesBeans and Balls! Hematoma Abscess Tumor
R/P mass in Neonate
Renal Hydronephrosis Multicystic dysplastic kidney Solid
Wilms tumor? Perinephric hematoma? Mesoblastic nephroma? Lymphoma?
Adrenal Hemorrhage neuroblastoma
Mesoblastic Nephroma(Fetal renal hamartoma) Most common neonatal renal neoplasm Present as an asymptomatic mass Not Wilms tumor
Characteristics Benign appearing spindle cells with dysplastic
nephrons Large (8-30cm), arise in medulla Blends with normal parenchyma May penetrate capsule and invade locally Rare hypercellular forms may metastasize
Mesoblastic Nephroma(Fetal renal hamartoma) Imaging
Non-calcified abdominal mass Look like uterine leiomyoma by US CT vascular and entrapped collecting
system excretes contrast
Mesoblastic Nephroma(Fetal renal hamartoma) Management
Nephrectomy No chemo or radiation (usually no mets) Cellular form
Age >3months at surgery are more likely to need chemo/radiation
Childhood Renal Tumors
Wilms tumor & nephroblastomatosis Renal lymphoma/leukemia Renal cell carcinoma Multilocular cystic nephroma Clear cell sarcoma Rhabdoid tumor Angiomyolipoma (and tuberous sclerosis)
Wilms Tumor
Most common solid abdominal mass in childhood
Most common renal malignancy in child 8% of all childhood cancer
Wilms Tumor
Demographics Male=female 1% familial 7.8 per 1,000,000 children Peaks between 2.5 to 3 years 80% occur between 1-5 years
Presentation Asymptomatic mass most common Other: pain, hematuria, hypertension, fever
Wilms Tumor
Associated conditions 8% have overgrowth disorders, genital
anomalies, aniridia Drash, Beckwith-Wiedemann, Soto, NF,
KTW, Bloom, WAGR, 45X, etc 5% bilateral & higher incidence of above
These children’s siblings have a 30% chance of development of Wilms
Nephroblastomatosis (Wilms precursor)
Wilms Tumor
Nephroblastoma (Wilms “in situ”) Rests of metanephric blastema persisting after 34-36
weeks gestational age Present in most cases of bilateral Wilms, 15%
unilateral disease Intralobular NR
Younger age Drash & sporadic aniridia Metachronous Wilms
Perilobular NR BWS, Tr18, hemihypertrophy Synchronous Wilms
Wilms Tumor
Nephroblastomatosis ImagingAppearance
Nodules Subcapsular hypodense plaques
US – iso, hypo, hyperechoic (relatively insensitive)
CT w contrast better for surveillance MRI ? Able to distinguish Wilms from
nephroblastomatosis
NR versus Wilms at MRI
NR Plaque-like Ovoid Lenticular Homogeneous on all
sequences Hypotense post gad
Wilms Round/spherical Heterogeneous pre
gad Heterogeneous post
contrast
Nephroblastomatosis
Treatment Confluent disease treated with
chemotherapy
Wilms Tumor
Pathology Solid, necrosis, hemorrhage, 15%
calcifications Capsule usually intact Invades nodes, veins, rarely urothelium Decreasing 10’s
10% renal vein invasion– 10% IVC extension
• 10% right atrial extension
Wilms Tumor
Pathology 5% bilateral 7% unilateral and multicentric Metachronous cases may occur up to 10
years later 10% unfavorable histology
Wilms Tumor
Pathology Lung mets up to 20% at diagnosis Liver mets 10% of patients Bone mets rare (lytic) Bilateral tumors may have different grades
of histology (favorable vs unfavorable)
Wilms Tumor
Staging I – limited to kidney, completely resected II- outside kidney, completely resected III – confined to abdomen IV – hematogenous mets V – bilateral initial/during treatment
Wilms Tumor - Radiology
Nitwits (NWTS) don’t agree on optimal imaging – nonsense like IVP’s persist
IVP – distortion of collecting system, non-function (vascular compression)
US – CDS excellent for venous tumor thrombi in IVC Echotexture similar to liver Sharply marginated
Wilms Tumor - Radiology
CT 15% contain calcifications Round, hetergeneous, low density Displaces vessels, does NOT encase
(DDX from neuroblastoma) Best for opposite kidney evaluation, nodes,
lungs
Wilms Tumor-Radiology
MRI Becoming preferred over CT Prolonged T1 and T2, heterogeneous post
gad Excellent for NR of 4 mm size
Angio Plays a role for partial nephrectomy
Wilms Tumor - Surveillance
Patients with syndromes associated with Wilms
US easiest, MRI may be best Arbitrary 3-6 month scans Continue until about 10 years old (<1%
incidence after 10)
Wilms Tumor - Treatment
Overall survival now 90% >90% survival @ 2 yrs with favorable
histology, surgery, chemo and radiation High mortality with unfavorable histology
Renal Lymphoma
Usually late in NHL Nodules, masses, diffuse infiltration Unilateral/bilateral US – hypoechoic CT – hypodense Leukemia usually diffuse/bilateral
Multilocular Cystic Nephroma
Indistinguishable from cystic partially differentiated nephroblastoma/cystic Wilms
Young boys and adult women Anechoic cysts with regular septa Rx - nephrectomy
Clear Cell Sarcoma
Identical age group to Wilms Very aggressive Not distinguishable from Wilms by
imaging Bone mets common
Other lesions to ponder
“Simple” cyst Were considered rare prior to ultrasound But, the differential diagnosis is:
Prior trauma or infection Obstructed upper pole moiety of duplication Early presentation of familial cystic disease
Other lesions to ponder
Duplication Hematoma/renal trauma Pyelonephritis
Focal bacterial Xanthogranulomatous
Autosomal recessive polycystic kidney dz Infantile form