Radiology of pediatric renal masses

1. ATRIC RENAL MASSES
By Dr Himanshu

2. TUMORS OF 1ST DECADE
WILMS
 Most Common ( 90 %)
 Origin : Renal precursor tissue known as
Metanephros/Mesenchymal Tissue (Mostly)
 Age : Mostly below 5 years, Peak at 2-3 years. Rare after 15 years
 Presents mostly as asymptomatic abdominal mass.
 Mostly solitary, 12% : Multifocal in one kidney, 7% : Involves Bilateral
kidneys.

3. Gross appearance
Pathology : Mostly Triphasic appearance

4. USG CT (Claw Sign)

5. MRI
T1 : Hypointense with
Hyperintense areas representing
haemorrhage.
T2 : Iso to Hyperintense
Gd Contrast study : Enhances
less avidly than adjacent kidney
with non-enhancing areas of
haemorrage/necrosis

6. May extend into Renal Vein/IVC/Even right heart

7. ROLE OF FDG-PET
 Can indicate anaplastic histology ( High SUVmax with poor response
to neoadjuvant Chemo)
 To Direct Biopsy.
 To know active residual/recurrent disease.

8. STAGING

9. TUMOR METASTASIZES TO LUNG(85%), LIVER (20%), RARELY TO BONE.
5 YEAR SURVIVAL RATE EXCEEDS 90% (70% OVERALL SURVIVAL RATE
IN STAGE 4)
D/D
1) Neuroblastoma:
i) Determine origin of tumor (Claw Sign)
ii) Calcification (15% vs 80-90% in Neuroblastoma)
iii) Tumor invasion vs encasement of vessels in
Neuroblastoma
iv) Tumor crossing midline
v) Extension through neural foramina into spinal canal
vi ) Skeletal Mets

10. 2) Pyelonephritis (focal)
i) Clinical features (fever,flank pain,urinary
symptoms)
ii) wedge shaped hypodense areas
3 ) Other Renal tumors

11. ASSOCIATED SYNDROMES( IN 10%)
WT1 (11p13) mutation or deletion (Most Common) : associated with WAGR
syndrome and Denys Drash Syndrome (Wilms tumor, male pseudo hermaphroditism and
progressive glomerulonephritis)
WT2 (11p15) : associated with overgrowth syndrome including
i) Beckwith-Wiedemann syndrome (macroglossia, omphalocele, organomegaly,GU
anomalies, increased risk of abdominal tumors) +/- hemihypertrophy
ii) Perlman Syndrome ( visceromegaly, gigantism,renal dysplasia, GU anomalies and
characteristic facies)
iii) Sotos Syndrome ( cerebral gigantism, renal anomalies, cardiac anomalies,Wilms
tumor)

12. WTX mutation (X chromosome)
B catenin mutation (chromosome3)
TP53 mutation ( on chromosome 17) – associated with anaplastic
histology and poor prognosis
Screening for Wilms tumor should start at 6months with serial USG every
3 months upto age of 8 years.

13. NEPHROBLASTOMATOSIS
 Multiple or diffuse nephrogenic rests
(persistent embryonal renal tissue)
 Found in 40% kidneys resected for Wilm’s
Tumor
 White to Tan Tissue in gross specimen.
 2 Types: i) Perilobar (More common) :
associated with overgrowth syndrome and
Trisomy 18
ii) Interlobar : associated with WT1
mutations

15. Increasing size or heterogeneity or assumption of spherical
configuration are suggestive of neoplastic transformation.

16. CYSTIC NEPHROMA AND CPDN
 Macroscopically similar, histologically distinct. Collectively known as
Multilocular cystic renal tumor.
 Represents benign end of spectrum with Wilms tumor being at
malignant end. No metastasis is seen.
 Age : 3 months to 4 years (M:F = 2:1)
 Mostly presents as asymptomatic abdominal mass.
 Genetic association : DICER 1 mutation, associated with cystic
pleuropulmonary blastoma.

17. Grossly : Cystic tumors with septations
Histologically: Septa are lined by Hobnail/flat/cuboidal cells.
Cells within the septa differentiates between Cystic Nephroma (mature
tubules) and CPDN (blastemal cells)
Nodules of blastemal cells instead indicate Cystic Wilms Tumor.

18. Imaging : Very small locules/cysts may appear as solid area
Herniation of tumor into collecting system

19. T2WI T1 Gd Enhanced Study

20. D/D
1) Wilms Tumor
2) Severe HDN : communicating cysts with a large one in pelvis
3) MCDK : a) Diagnosed prenatally or at birth
b) absence of compressed renal parenchyma surrounding the
cysts
4) Segmental Dysplasia: associated with Duplex Kidneys.
5) Hereditary Cystic Kidney Disease.

21. CONGENITAL MESOBLASTIC
NEPHROMA(CMN)
 Rare, but most common renal neoplasm of neonate
 Age: MC before 3 months, mostly by 1 year. Not after 2 years. M:F =
1.5:1
 Can be diagnosed prenatally.
 Majority (70%) are associated with perinatal complications :
Polyhydramnios, Hydrops fetalis, Preterm Delivery
 Mostly Benign with good survival, 5-10% shows local recurrence or
mets.
 2 Types

22. Homogenous, “Ring sign” : concentric
hyperechoic and hypoechoic rims
surrounding tumor. No necrosis
Classical Type

23. Cellular type can show recurrence after treatment, thus USG follow up is recommended
till 1 year
Cellular Type
Heterogeneous tumor with anechoic cysts Large fluid attenuation cyst

24. CLEAR CELL SARCOMA
Rare, however most common malignant tumor after Wilms tumor
Mean age : 36 months, rare before 6 months with M:F= 2:1
Noted for its propensity to metastasize to Bones (lytic, sclerotic,
mixed)
Imaging features are non specific, however similar to Wilms tumor

25. RHABDOID TUMOR
Rare and aggressive. Worst prognosis of any pediatric renal
malignancy.
Age: <2 years , mean age being 11 months. M:F=1.5:1
Uniquely associated with Intracranial Neoplasms.
Central; arises from medulla
Hematuria is a common presenting feature due to invasion of renal
collecting system. Vascular invasion is common.
Genetics: loss of INI-1 (ch 22q)

26. Imaging : Mostly similiar to Wilms Tumor (however calcifications is more
common :70% vs 15%)
T2WI: Subcapsular fluid signal intensity (nonspecific) Posterior Fossa Tumor with
necrosis

27. OSSIFYING RENAL TUMOR OF
INFANCY(ORTI)
Extremely rare. Benign.
Age: <30 months. Male predilection
Hematuria is usual presenting feature as they can grow in renal
calyx/pelvis.
Usually calcified

28. Echogenic foci with PAS Mimicks Staghorn Calculus, however show variable enhanc

29. RENAL TUMORS OF 2ND
DECADE
RENAL CELL CARCINOMA
 2nd most common renal malignancy of childhood after Wilms,
however most common in 2nd decade of life.
 Most common type: Translocation RCC> Papillary RCC> Medullary
RCC. Rest rare.
 Lymph node spread is more common.

30. TRANSLOCATION RCC
Xp11.2 translocation leading to overexpression of TFE3
Risk factor : History of cytotoxic chemotherapy during childhood
May show Renal vein thrombosis

31. Imaging
USG : Heterogeneous mass with focal/rimlike calcifications
NCCT : Hyper attenuating compared to adjacent cortex +/-
calcifications.

32. CECT : Heterogenous +/- calcifications with enhancing capsule.

33. MRI : Heterogeneous signal intensity with dark rim/capule
T2WI Gd enhanced fat saturated T1

34. Medullary Carcinoma
 Patient history of Sickle Cell Trait
 Infiltrative growth pattern however reniform shape is preserved
 Extends into collecting system ; caliectasis without pelviectasis
 Metastatic disease is common at presentation.

35. ANGIOMYOLIPOMA
 Almost always associated with TSC (multiple, large, Bilateral)
 Mean age : 10 years
 Usually Asymptomatic
 May cause hemorrhagic complications manifesting as pain, anemia,
hypovolemic shock due to aneurysm formation ( > 4 cm )
 Benign , however show locally aggressive growth ,especially after
puberty in girls suggesting hormonal influence

36. Histologically
Fat cells and vessels with thick walls
USG
Echogenic fatty portions without PAS, may show flow

37. CT
Heterogeneous with fatty attenuation component
MRI
Fat component is hyper intense on T1 and T2 with suppression of
signal in fat s saturated images
Vascular component may enhance intensely after contrast study

38. Epitheloid angiomyolipoma
 Rare variant in patients with TCS
 Frequently contain fluid-attenuating necrosis and hemorrhage,
calcifications but generally no fat
 Invade adjacent tissues and even shows metastasis.

39. METANEPHRIC TUMORS
 Originate from metanephric blastema ( same as Wilms tumor)
 Comprise of spectrum of Epithelial and stromal tumors
Metanephric adenoma ( purely epithelial) : Mean age 41years
(Female predilection)
Metanephric Stromal Tumor ( purely stromal) : Mean age 2
years
Metanephric adenofibroma (epithelial + stromal) : Mean age
82 months
 Mostly found incidentally
 Considered Benign but some case of metastasis have been reported

40. Imaging Features
USG : Well defined, show variable echogenicity (mostly hyper echoic)
CT : Hyper dense lesion with hypo dense areas (necrosis, hemorrhage) and
may show central/ peripheral calcifications.

41. LYMPHOMA
 No Renal lymphoid tissue so lymphomatous involvement of kidney
occur by hematogenous spread or direct extension of a
retroperitoneal mass.
 Most common : Burkitt Lymphoma
 May be solitary but often multiple, bilateral expansile renal
masses/nodules
 Rarely involves only kidneys

42. Imaging
USG
Multiple round masses or nodules,
hyper echoic < hypo echoic (with PAE) mimicking cyst.
CT
Round hypodense lesions involving both kidneys Diffuse wall thickening of ileum

43. PRIMITIVE NEUROECTODERMAL
TUMOR
 Highly aggressive small round cell tumor, most commonly affects
Bones and rarely Kidney
 Characteristic Chromosomal translocation: t(11;22) (q24;q12)
producing fusion protein EWS-FLI1
 Mean age : 24-27 years
 CD99 positive
 Imaging : Quite large at presentation replacing kidney,
heterogeneous with necrosis, hemorrhage, calcification.
 May invade Renal Vein and IVC.

44. DESMOPLASTIC SMALL ROUND
CELL TUMOR
 Rare, aggressive
 Strong predilection for males aged 5-30 years
 Translocation t(11;22)(p13;q12) creates EWS-WT1 gene fusion.
 Typically appears as disseminated peritoneal and mesenteric
disease involving large dominant mass, most often in retrovescical
region. Single organ involvement is rare
 Imaging features of mass are somewhat similar to Wilms tumor.