Wilms Tumour Flashcards
Introduction to Wilms tumour overview
Nephroblastoma
Affects children 2-4 years old
Presents as asymptomatic abdominal mass in children
Most unilateral
85% survival rate
Children oncology group (cog): immediate nephrectomy
International society of pediatric oncology(SIOP): nephrectomy follows a short course of chemotherapy
Wilms tumour Etiology
7 in a million in USA
6% of all renal tumour in children
Black children & girls more affected
75% in healthy children; 25% in other genetic abnormalities
Risk factors for Wilms tumour
- African American race
- Family history of Wilms tumour
- Other genetic abnormalities
Genetic abnormalities associated with Wilms tumour
- Beckwith-wiedemann syndrome (omphalocele, macroglossia, vesceromegaly)
- Denny-DARSH syndrome (Wilms tumour, kidney disease, male pseudohermaphroditism )
- WAGR syndrome (Wilms tumour, aniridia, genital abnormalities, mental retardation)
How genetic abnormalities occur
WT1 gene- tumour suppressor gene on chromosome 11p13
Beckwithwiedemann syndrome= loss of heterozygosity at chromosome 11p15, WT2 gene may be situated at this locus
Deny-crash syndrome=point mutation in 11p13
WAGR=gene 11p13 is deleted
Wilms tumour pathology
Typical appearance of tumour: solid+cystic+hemorrhagic regions
Gross: large, solitary, well circumscribed mass w remaining rim of normal kidney
Cut: soft, homogenous, tan-grey in colour; with areas of necrosis & hemorrhage
Pathological: origin is metanephric blastema- 3 elements (blastemal, stromal, epithelial)
Divided into 2 prognostic group pathologically:
1. Favourable- well developed components
2. Unfavourable: contains Anaplastic cells, focal/diffuse
Clinical features in Wilms tumour
- Abdominal mass: 75% will not cross midline
- Abdominal pain: 28%
- Hypertension: 26%
- Hematuria: gross18%; micro24%
- Fever: 22%
- Pulmonary metastases: 15%
- Involvement of renal vein, inferior vena cava: or atrium: 8%
Clinical features in Wilms tumour
- Abdominal mass: 75% will not cross midline
- Abdominal pain: 28%
- Hypertension: 26%
- Hematuria: gross18%; micro24%
- Fever: 22%
- Pulmonary metastases: 15%
- Involvement of renal vein, inferior vena cava: or atrium: 8%
Investigations in Wilms tumour
Aim: evaluate the site, size, extent of tumour & presence of secondaries & kidney functioning status
Types of investigations in Wilms tumour
- Plain abdominal radiograph: displacement of abdominal organs & presence of calcifications (10% at edge of tumour)
- Abdominal usg: confirm site of tumour, determine solid/cystic tumour, indicate extent like into renal veins & IVC
- CT scan: defines tumour site, presence of enlarged lymph node, presence of second Wilms tumour in the opposite kidney, assess involvement of the tumour into renal veins, IVC, RA; determines intra-abdominal secondaries to the liver. Note the thin rim of remaining kidney ‘claw sign’.
- MRI- coronal view- T1 hypointense & T2 mixed/hyperintense. Useful in assessing bilateral disease, vascular involvement, nephroblastomatosis
Wilms tumour investigation
Take note:
25-40%, additional abnormal cell clusters can be found within normal parts of the kidney
Called “nephrogenic rests”
Rarely, both kidneys consists of diffuse nephrogenic rests- pathology known as “nephroblastomatosis”
Nephroblastic rest= homogenous
Wilms tumour= heterogenous
Children oncology group (cog) staging
1- tumour limited to kidney, completely excised without rupture/biopsy. Surface of the renal capsule is intact
2- tumour extend through renal capsule, vessels outside the kidney contains tumour.
Other category: kidney has been biopsied before resection/ local spillage of tumour (during resection) limited to the tumour bed
3- residual tumour is confined to the abdomen, not from hematogenous spread.
Other category: tumour involvement of abdominal lymph nodes, rupture of tumour with ‘diffuse’ peritoneal contamination extending beyond tumour bed
4- hematogenous metastases at any site
5- bilateral renal involvement
Society of pediatric oncology (SIOP) staging
1- tumour limited to kidney, complete excision
2- tumour extending outside the kidney, complete excision, invasions beyond
- capsule, perirenal, perihilar
- regional lymph node
- extra-renal vessels
- ureter
3- tumour beyond the capsule with incomplete excision
- preoperative/perioperative biopsy/rupture
- peritoneal metastases
- invasion of para-aortic lymph node.
- incomplete excision
4- distant metastases
5- bilateral renal tumour
Differential diagnosis of Wilms tumour- neuroblastoma
Both are abdominal mass
- Primary origin:
Wilms tumour- intrarenal
Neuroblastoma- extrarenal (from adrenal gland, para vertebral sympathetic ganglia) - Physical examination:
Wilms tumour- displacing mass, mainly confined to flank
Neuroblastoma- non-mobile mass, likely to cross midline - Pattern of tumour spread:
Wilms tumour- direct expansion with displacement of adjacent structures
Neuroblastoma- encasement of vessels & aortic elevation - Other
Wilms tumour- intrinsically displaces urinary collecting systems
Neuroblastoma- externally displaces kidney, neural extension, often calcified
Treatment of Wilms tumour
Stage 1&2 + favourable histology= nephrectomy + 18 weeks chemo (vincristine + dactinomycin)
Stage 3 + favourable histology= nephrectomy + tumour bed/whole abdomen irradiation + 21 weeks of combination chemotherapy (vincristine, dactinomycin, doxorubicin)
Stage 4 + favourable histology= nephrectomy + whole lung irradiation + 21 weeks of combination chemotherapy (vincristine, dactinomycin, doxorubicin)
Note: full doses of drugs given after 12 months. Below that, half of recommended doses.
