Renal Masses Robert D. Thomas MD Pediatric Radiology

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