Robert D. Thomas MD Pediatric Radiology Renal Masses Robert D. Thomas MD Pediatric Radiology

Renal Masses Balls Beans Cyst Hematoma Abscess Tumor Dromedary hump Duplication/anomaly Compensatory hypertrophy Hydronephrosis Pyelonephritis/edema Hematoma PCKD Tumor Vascular occlusion/trauma

Renal Masses by Age Newborn Childhood Hydronephrosis Cysts 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 Kidney Bean 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 Masses Beans and Balls! Hematoma Abscess Tumor

R/P mass in Neonate Renal Adrenal 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 Presentation 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 Wilms 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