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2010-06-11-10 Wilms' tumor © Ha www.TheFetus.net
Wilms' tumor

Nguyen Ha, MD.*, Eva Leinart, MD., PhD.**

*  Director of Imaging Diagnosis Department, Maternal Tudu Hospital, 284 Cong Quynh St Dist 1, Hochimin City, Vietnam.  
** Inner Vision Women's Ultrasound, Nashville, Tennessee, USA.
  

Introduction

Wilms' tumor (nephroblastoma) is a embryonal neoplasm consisting of epithelial, stromal and blastemal elements. Not all Wilms' tumors contain all three types of cells. It is very likely a result of abnormal proliferation and differentiation of metanephric blastema. Prenatal occurrence of this tumor is very rare. The incidence of Wilms' tumor is 1:10,000 births.
Prenatal occurrence of this tumor is very rare, only 0.16% of all cases of Wilms' tumor.

15 % of cases may have some associated anomalies, such as aniridia, hypospadia, undescended testes and hemihypertrophy. There are certain syndromes associated with Wilms' tumor: Beckwith-Wiedemann, Denys-Drash, WAGR (Wilms tumor, aniridia, genital anomalies, retardation), Frasier, Genitourinary anomalies without renal failure.

Chromosome 11 plays a role in pathogenesis of this tumor, WT1 gene is the only gene which had been identified. 10-15 % of cases are considered to be heritable. Genetic counseling for specific syndrome is appropriate after diagnosing a individual with Wilms' tumor. Prenatal diagnosis for pregnancies which are in 50% risk of inheriting  WT1 mutation from their affected parents is possible (amniocentesis or chorionic villus sampling). WT1 mutation of the parent must be known before the testing is performed.

Ultrasound findings

  • Solid echogenic renal mass
  • Well-defined capsule
  • Possible areas with hemorrhage or necrosis
  • Increased amount of amniotic fluid
  • Fetal hydrops may develop


Differential diagnosis

1) Congenital mesoblastic nephroma; this tumor doesn't have a well-defined capsule, can bleed within the normal renal parenchyme, is often associated with increased amount of the amniotic fluid and can cause fetal hydrops.

2) Adrenal neuroblastoma; most common neonatal abdominal tumor, separate from kidney, located in retroperitoneum, heterogeneous with solid and cystic components. Produces catecholamines and their high level in the maternal circulation can cause maternal symptoms.

3) Retroperitoneal teratoma; very rare, cystic appearance.

Prognosis

Prognosis depends on stage, histological type and presence of metastases. The treatment of choice are nephrectomy, tumor resection and regional lymph node sampling followed by chemotherapy and/or radiotherapy. Favorable histological type for stages I-III has survival rate around 90% (staging criteria were modified by Children's Oncology Group).

Pregnancy may be complicated by an increased amount of the amniotic fluid and fetal hydrops. This may be lead to a preterm birth or intrauterine fetal demise.

Case report

This is a case 28-year-old G1 P0 who was referred to our department at 32 weeks of gestation. Her family and personal history was non-contributive. The ultrasound scan showed a round vascularized mass in the right kidney. There was an increased amount of the amniotic fluid as well, AFI=41 cm. Our differential diagnosis included: Mesoblastic nephroma and Wilms' tumor.

Patient delivered via emergency cesarean section. The ultrasound scan performed after delivery confirmed a kidney tumor. The neonate underwent nephrectomy. The final diagnosis according to the pathologist was Wilms' tumor. The baby is 4 months old at the moment and underwent 6 series of chemotherapy already.

Images 1,2: Image 1 shows a parasagittal section of the fetal abdomen showing the round capsulated cystic lesion in the renal region. Image 2 shows a transverse view of the abdomen with a tumor in the right kidney. Left kidney is of a normal appearance.



Images 3,4: Image 3 shows a transverse view of the kidney tumor. Image 4 shows a vascularization of the tumor.



Images 5,6: Images show a vascularization of the tumor.



Images 7: increased amount of the amniotic fluid.



References:

1. Vadeyar S, Ramsey M, James D, O'Neill D. Prenatal diagnosis of congenital Wilms' tumor(nephroblastoma) presenting as fetal hydrops. Ultrasound Obstet Gynecol 2000; 16:80-83.
2. Hrabovsky EE, Othrsen HB, deLorimier A, Kelalis P, Beckwith JB, Takashima J. WIlms' tumor in the neonate: a report from the national Wilms' tumor study. J Pediatr Surg 1986; 213:385-387.
3. Breslow NE, Beckwith JB. Epidemiological features of Wilms' tumor: results of the National Wilms' tumor study. J Natl Cancer Inst 1982; 68:429-436.
4. Beckwith JB. Wilms' tumor and other renal tumors of childhood: a selective review from the National Wilms' tumor Study Pahology Center. Human Pathol 1983;14:481-492.
5.Ohmichi M, Tasaka K, Sugita N, Kamata S, Hasegawa T, Tanizawa O. Hydramnios associated with congenital mesoblastic nephroma: case report. Obstet Gynecol 1989;74:469-471.


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