The pediatric urologist deals with a variety of benign and malignant genitourinary tumors which can be grouped in the following manner:
1. Tumors of the upper urinary track.
2. Tumors of the adrenal gland and retroperitoneum.
3. Tumors of the lower urinary track.
Most children with genitourinary tumors will present with specific symptoms such as voiding problems and/or non-specific symptoms such as pain, weight loss, anemia or fever, depending on the organ of origin and the presence of metastatic disease. Gross hematuria is uncommon. A mass may be palpable in the abdomen, flank, pelvis or genitals. Hypertension may be found. Investigation with a sonogram and VCUG will usually define the site of origin. A CT will help to delineate the size and extent of the mass. A chest x-ray and bone scan (when indicated) will further help define the stage of the disease.
TUMORS OF THE UPPER URINARY TRACK
1. Wilms Tumor
Wilms tumor (nephroblastoma) is the most common malignant tumor of the urinary track in children. The peak age for this tumor is about three years and occurs in 1 in 250,000 children per year. The tumor occurs in either a heritable or non-heritable form.
There are some uncommon associated congenital anomalies such as hemihypertrophy, Beckwith-Wiedemann syndrome, sporadic aniridia and other genitourinary anomalies such as ectopy, duplication, etc.
Bilateral Wilms occurs in a small percentage of children and may be synchronous or metachronous. Bilateral tumors are usually associated with favorable histologic patterns.
Treatment is primarily surgery followed up with chemotherapy (actinomycin D, vincristine and doxorubicin) and possibly radiotherapy.
2. Mesoblastic nephroma.
This tumor is a possible benign variant of Wilms tumor seen in early infancy.
3. Other tumors
Other tumors include nephroblastomatosis, renal cell carcinoma, sarcoma, and benign tumors of the renal pelvis and ureter.
TUMORS OF THE ADRENAL AND RETROPERITONEUM
Neuroblastoma is a tumor of the sympathetic ganglia and the peak age at presentation is 1 1/2 years. 70% of children with this tumor present with metastatic disease.
Bone metastases and bone marrow invasion leading to thrombocytopenia are common. A third of these tumors have calcification in the primary site. Breakdown products of catecholamine metabolism are found in 90%.
There is a high spontaneous regression in infancy and maturation to ganglioneuromas.
Treatment is primarily surgery followed by chemotherapy and possibly radiotherapy. Second look procedures may be indicated.
Prognosis is affected by age and site. Those under two years and those with pelvic tumors have a better prognosis. Overall prognosis is poor.
2. Other retroperitoneal tumors
Other less common retroperitoneal tumors are pheochromocytoma, adrenocortical tumors and teratomas. Most teratomas arise in gonadal tissue but others arise in pre-sacral or sacrococcygeal sites.
TUMORS OF THE LOWER URINARY TRACK
Rhabdomyosarcomas of bladder, prostate, uterus, vagina and spermatic cord are important tumors in this area. The majority occurs in those under the age of five years. A prostatic rhabdosarcoma must be considered in any boy with voiding difficulty and/or hematuria. Girls with rhabdosarcomas present with a vaginal discharge and/or an inter labial mass
Treatment of pelvic rhabdosarcomas is directed at biopsy followed by multi-agent chemotherapy. If there has been significant tumor shrinkage on subsequent clinical evaluation, chemotherapy is continued to 16 weeks. The patient then undergoes laparotomy with excision of residual tumor. With this regimen, it is often possible to perform a radical prostatectomy or partial cystectomy. Chemotherapy is continued postoperatively. Radiation may be added.
2. Testicular tumors
Testicular tumors are rare and must be differentiated from torsion, hydrocele, hernia, trauma, epididymitis and paratesticular tumors. 75% of testicular tumors in pre-pubertal boys are of germ cell origin.
A. Germ cell tumors
1. Infantile embryonal carcinoma (Yolk sac carcinoma).
This is the most common primary malignant testis tumor of germinal origin in children. These tumors can produce alpha-fetoprotein, which may be a good marker.
This tumor is usually benign.
This tumor is mostly restricted to patients with mixed gonadal dysgenesis and, in particular, those with mosaic chromosomes. 25% of these tumors are malignant.
Treatment involves orchiectomy. Combination chemotherapy is given for advanced disease. This may be followed by retroperitoneal lymphadenectomy and/or radiotherapy. Chemotherapy continues post-operatively.
B. Non-germ cell tumors (stromal origin)
These include Leydig, Sertoli, adrenal rest, accessory spleen, paratesticular rhabdomyosarcoma and metastatic diseases. Leydig and Sertoli cell tumors can give rise to precocious pubertal changes but usually only breast hypertrophy in Sertoli cell tumors.
When an orchiectomy is necessary, a plausible cosmetic solution (for physical appearance not functional sake) is an artificial implant. (See Saline-Filled Testicular Implant.)