Radiologic Diagnosis of Wilms Tumor

Adam FriedmanGillian Lieberman, MD

March 2008

Patient presentation

• Two year old male with abdominal pain, swelling and constipation.

Our patient: RUQ mass on abdominal plain film

Study: Abdominal X-Ray

Findings:

• Dilated large and small bowel, leftward displacement

• Soft tissue density in right upper and lower abdomen obscuring lower liver margin

Our patient: Heterogeneous mass on ultrasound

Study: RUQ ultrasoundFindings: • Heterogeneous, septated, soft tissue mass, 9 x 10 x 6cm, with solid

and cystic components (anechoic regions with enhanced through- transmission).

• Doppler demonstrates regions of vascular flow in addition to cystic elements

Differential diagnosis

• Wilms Tumor• Neuroblastoma• Hepatoblastoma• Nephrogenic rests or nephroblastomatosis (multifocal

or diffusely bilateral nephroblast remnants)• Other abdominal soft tissue masses:

– Rhabdomyosarcoma– Lymphoma– renal cell carcinoma (adults)

Our patient: Heterogeneous mass on axial CT

r. kidney

mass

l. kidney

Our patient: Heterogeneous mass on coronal CT

l. kidney

spleen

r. kidney

mass

Our patient: Summary of findings on CT

Study: Abdominal CT with oral and IV contrast, late arterial phaseFindings:

• 10.5 x 9.3 x 12.2 cm cystic heterogeneous mass within the right hemiabdomen, originating from upper/middle poles of kidney

• Mass-effect shift of liver• Narrowing and deviation of infrahepatic IVC• “Claw sign” of engulfment by right kidney• No evidence of renal vein or IVC thrombosis• No evidence of pulmonary metastatic disease

Diagnosis: Wilms Tumor

• Wilms Tumor, with cystic elements and favorable histology.

• Stage III due to lymph node metastases and tumor rupture noted intra-operatively, with adherent liver metastases

Radiologic features of Wilms Tumor

• “Claw Sign”: Concavity of the renal contour with renal parenchyma cupping the tumor/cyst

• Clawing suggests organ of tumor origin. • Major differential is neuroblastoma, a neuroendocrine

tumor of neural crest origin):• Neuroblastoma: Displacement of kidney, adrenal origin, encasement

of IVC/aorta, 90% calcifications• Wilms: Engulfment of kidney, origin from renal parenchyma,

displacement of vessels, 15% calcification

Neuroblastoma vs. Wilms Tumor

NeuroblastomaDisplacement of kidney

adrenal originencasement of IVC/aorta

90% calcifications

Wilms Tumorengulfment of kidney

origin from renal parenchymadisplacement of vessels

15% calcification

companion patient #1 companion patient #2 companion patients #3-4

Wilms Tumor: embryology, epidemiology, biology

• Derived from remnant rests of embryonic nephroblastic cells• Associated with WT1 transcription factor tumor suppressor • 6% of all childhood cancers, 1:10,000 incidence, with peak incidence between 2-5• Cure rates ~85%• Associated syndromes include (WAGR), Beckwith-Wiedemann, Denys-Drash,

horseshoe kidney• 5% bilateral, 5% metastatic (lung, lymph nodes, liver); 6% extend into IVC or RV• Nephrogenic rests (intralobar or perilobar) increase risk for WT (but only ~1%)• Histologically: blastemal, stromal, epithelial cells

Wilms Tumor: the role of imaging

• Ultrasound: Hypervascular, heterogenous mass• CT: solid, heterogenously enhancing, solitary renal mass

(can be bilateral); calcifications in <20%• MRI: Hypointense on T1, hyperintense on T2, with

heterogeneous enhancement

• CT used for staging due to superior resolution of lung metastases (vs. bone scanning for neuroblastoma)

• U/S monitoring of high risk (syndromic) patients every 3-4 mo until 7 yo

Wilms Tumor: staging and therapy

• Staging:• I - Unilateral, intact renal capsule, total excision• II - Regional tumor extension, total excision• III - Residual tumor, confined to abdomen• IV - Metastases (lung, liver, bone, brain)• V - Bilateral

• Treatment:• Nephrectomy (if IVC not involved)• Chemotherapy (vincristine/actinomycin D, +/- doxorubicin, etoposide,

carboplatin)• Preoperative chemotherapy in Europe for down-staging, vs. post-op in

US.• Radiation (<30%)• Routine U/S monitoring

Advanced imaging modalities in Wilms Tumor

• 3D MRI tumor perfusion mapping• DWI/ADC MRI mapping• FDG-PET/CT

Preoperative 3D mapping of tumor perfusion

• Maximum contrast (absolute) or maximum slope of contrast enhancement during MRI used to correlate areas of necrosis and perfusion of nephroblastomas or neurblastomas for surgical planning.

companion patient #5

Apparent diffusion coefficient (ADC) mapping

• Contrast-enhanced T1 MRI vs. ADC map• Rim-enhancement and interior architecture prominent with

ADC map• ADC mapping may indicate early tumor response, before

clear tumor shrinkage (late finding)

companion patient #6

FDG-PET/CT

• Companion patient #6 with renal cell carcinoma• 18F-fluorodeoxyglucose positron emission tomography (FDG-PET)

imaging reveals areas of increased metabolic activity• Developing utility in Wilms Tumor:

• Targeting biopsy to most aggressive elements• Monitoring treatment response• Identification of metastatic lung foci

Summary

• Discussion of 2 y.o. boy with Stage III Wilms Tumor• Radiologic diagnosis of WT vs. neuroblastoma• Utility of “claw sign”• Review of Wilms Tumor embryology, biology• Advanced radiologic tools for WT diagnosis and tracking

Acknowledgments and References

Acknowledgments:

• Jay Pahade, M.D.• Gillian Lieberman, M.D.

References:• Kaste SC, McCarville MB. (2008) “Imaging pediatric abdominal tumors.” Semin Roentgenol., 43(1): 50-9.• Günther, P, et al. (2008) “3D Perfusion Mapping and Virtual Surgical Planning in the Treatment of Pediatric

Embryonal Abdominal Tumors,” Eur J Pediatr Surg. 18(1):7-12.• University Hospitals of Cleveland, www.uhrad.com, 2008.• Owens, CM, et al. (2008) “Bilateral disease and new trends in Wilms tumour.” Pediatr Radiol., 38(1): 30-9.• Kaste SC, et al. (2008) “Wilms tumour: prognostic factors, staging, therapy and late effects.” Pediatr Radiol., 38(1): 2-

17. • Ros, P. (eds), Mortele, K., Pelsser, V., Lee, S. (2007) CT And MRI of the Abdomen And Pelvis: A Teaching File,

Lippincott Williams & Wilkins• Olsen, OE and Sebire, NJ (2006). “Apparent diffusion coefficient maps of paediatric mass lesions with free-breathing

diffusion-weighted magnetic resonance: feasibility study.” Acta Radiol, 47:198–204.• Schedl (2007). “Renal abnormalities and their developmental origin.” Nat. Rev. Gen., 8: 791-802.• Eubank, WB, et al. (1998). “Imaging of oncologic patients: benefit of combined CT and FDG PET in the diagnosis of

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