WILMS TUMOR

Wilms Tumor : This is the most common solid intra-abdominal tumor (malignant) in children. It affects 450-500 children annually in the USA. Neuroblastoma is most common, but they are not all confined to the abdomen. It has a peak incidence at 3-5 years of age. Present as abdominal or flank mass with abdominal pain, asymptomatic hematuria, and occasionally fever. Other presentations: malaise, weight loss, anemia, left varicocele (obstructed left renal vein), hypertension. Abnormalities associated with Wilms tumor include hemihypertrophy, pseudohermaphroditism, aniridia, Beckwith-Wiedemann syndrome, trisomy 18 and other genitourinary anomalies.

The initial evaluation consist of: abdominal films, ultrasound, IVP, urinalysis, and chest-X-rays and
tomography. The presence of a solid, intrarenal mass causing intrinsic distortion of the calyceal collecting system is virtually diagnostic of Wilms tumor. Sonography can be of help to evaluate the IVC and renal veins (venous extension of the tumor). Metastasis most common in the lung and occasionally the liver.

Operation is for both treatment and staging to determine further therapy. The abdomen is explored by
a large transverse incision and both kidneys are visualized. Nodes are biopsied to determine extent of disease.
Staging by National Wilms Tumor Study Group:
Group I- tumor limited to kidney and completely resected.
Group II- tumor extends beyond the kidney but is completely excised.
Group III- residual non-hematogenous tumor confined to the abdomen.
Group IV- hematogenous metastasis.
Group V- bilateral tumors.

Further treatment with chemotherapy or radiotherapy depends on staging and histology (favorable vs
non-favorable) of tumor. Non-favorable histologic characteristics are: anaplasia (enlarged nucleus 3X,
hyperchromatism, mitosis), sarcomatous or rhabdoid degeneration.

Disease-free survival is 95% for Stage I and approximately 77% for all patients. Poor prognosis for
those with lymph nodes, lung and liver metastasis. Congenial Mesoblastic Nephroma presents in infants under 30 days of age (< 6 months), is commonly benign and invasive locally. Operative removal is curative, ruptured of tumor increases recurrences. Chemo, radiotx not indicated.