Wilm's Tumor (nephroblastoma)

Bharat R Agarwal
Pediatric Hematologist- Oncologist, Division of Pediatric Hem-Onco, B.J. Wadia Hospital for Children, Mumbai, India
First Created: 01/04/2001 

Introduction

Wilm's tumor is the second most common abdominal tumor and it makes up to 6% of all childhood cancer.

Presentation

Wilm's tumor commonly occurs as an abdominal or a flank mass with abdominal pain, hematuria, hypertension. There may be associated findings of fever, anorexia, vomiting, and features suggestive of metastatic disease to the lung, liver, and brain.

Nephroblastoma - Diagnosis

A child who presents with a flank mass may have any of the following conditions:

  • Neuroblastoma

  • Hydronephrosis

  • Multicystic kidney

  • Abdominal lymphoma

On clinical suspicion, the following investigations should be done to confirm the diagnosis:

  • Ultrasound of abdomen: to find out the tumor extent, calcification, lymph node, liver and opposite kidney status.

Abdominal CT scan: for evidence of bilateral involvement, the involvement of blood vessels with tumor.

Other investigations that are required are Biochemical profile, Chest X-ray, CBC, bone marrow aspiration (to rule out clear cell carcinoma of the kidney).

Also, since the Wilm's tumor gene, WT-1 is located on the short arm of chromosome 11(band 11p13), it may be associated with congenital anomalies like aniridia, hemihypertrophy, and Beckwith- Wiedmann syndrome.

In fact, it is now recommended that patients with aniridia or hemihypertrophy should be screened with Ultrasound every 3 months until they are 6 years of age. Also, children with Beckwith-Wiedemann syndrome should be screened with ultrasound every 3 months until they are 7 years old.

Hereditary Wilm's tumor (presents as either bilateral tumor or with a family history of the neoplasm) is uncommon with only 4 to 5% of patients having bilateral tumors and 1 to 2% having a positive family history of Wilm's tumor. The chance of bilateral Wilm's tumor occurring is higher in children in whom the original unilateral Wilm's tumor was diagnosed at less than 12 months of age or in whom the resected kidney contained nephrogenic rests.

Hence it is recommended that for early detection of metachronous bilateral Wilm's tumor, periodic abdominal ultrasound should be done in following patients:

  • Children with nephrogenic rests in the resected kidney (if <48 months of age at initial diagnosis) - every 3 months for 6 years.

  • Children with nephrogenic rests in the resected kidney (if >48 month of age at initial diagnosis) - every 3 months for 4 years.

  • Other patients - every 6 months for 2 years and then yearly for an additional 1 to 3 years.

Histopathology

Although most patients with a histopathological diagnosis of Wilm's tumor do well with treatment, there are 2 categories of unfavorable histology:

  • Anaplasia

  • Sarcomatous changes (includes clear cell sarcoma of the kidney and malignant rhabdoid tumor of the kidney.)

Nephroblastoma - Staging

The National Wilm's tumor study group has given a clinicopathologic staging system. The pediatric surgeon determines the clinical stage in the operation theatre and pathological staging is confirmed by the pathologist.

Stage I: Tumor is limited to the kidney and is completely excised. It is seen in 43% of patients.

Stage II: Tumor extends beyond the kidney through the perirenal capsule and is incompletely excised. It is seen in 23% of the patients.

Stage III: Residual tumor confined to the abdomen. No hematogenous involvement. It is seen in 23% of the patients.

Stage IV: Hematogenous metastases to lung, liver, bone, brain, or combination of these sites. It is seen in 10% of the patients.

Stage V: Bilateral renal involvement at the time of initial diagnosis. It is seen in 5% of the patients. Each site should be staged according to the above criteria on the basis of the extent of the tumor prior to biopsy.

Nephroblastoma - Prognosis

Though Wilm's tumor is curable in almost 90% of the patients, the prognosis is related to the stage of the disease at diagnosis, the histologic features, age of the patients and the tumor size.

Nephroblastoma - Treatment

Treatment of Wilm's tumor consists of a combination of surgery (nephrectomy) followed by chemotherapy and in some patients, radiation therapy. It all depends on the histology and stage of the disease.

National Wilm's Tumor Study IV Recommendations are:
Stage I Favorable history or anaplastic: Nephrectomy + Chemotherapy (vincristine + Actinomycin D) x 6 months. No Radiotherapy

Stage II Favorable histology: Nephrectomy + chemotherapy (vincristine + Actinomycin D) x 15 months. No Radiotherapy.

Stage II (Anaplastic),III & IV: Nephrectomy + Radiotherapy + chemotherapy (vincristine + Actinomycin D + Adriamycin) x 15 months.

Clear cell sarcoma (stage I to V): Nephrectomy + Radiotherapy + chemotherapy (vincristine + Actinomycin D + Adriamycin) x 15 months

Nephroblastoma - Follow Up

As stated earlier, abdominal ultrasound is done once in 6 months for two years and then yearly for an additional 1 to 3 years. A chest X-ray should also be repeated at the same time. The patient with the pulmonary disease at diagnosis should have a repeat CT scan every 3-6 monthly for 2 years and then yearly for 1-3 years.


Wilm's Tumor (Nephroblastoma) Wilm's Tumor (Nephroblastoma) Wilm's Tumor (Nephroblastoma) 01/04/2001
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