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| Wilms' tumor |
An embryonal renal neoplasm containing blastema, stromal or epithelial cell types usually affecting children before the 5th year.Several congenital anomalies are known to be associated with Wilms' tumor. A two stage mutational model has been proposed: occurrence in either hereditary form or sporadic form. Patients with aniridia have a deletion of the short arm of chromosome 11 (11p13).
SIGNS AND SYMPTOMS:
•Usually asymptomatic
•Palpable upper abdominal mass
•Abdominal pain
•Fever
•Anemia
•Rarely, signs of acute abdomen with free intraperitoneal rupture
•Cardiac murmur
•Hepatosplenomegaly
•Ascites
•Prominent abdominal wall veins
•Varicocele
•Gonadal metastases
CAUSES:
•Hereditary or sporadic forms of genetic mutation
•Familial form: autosomal dominant trait with incomplete penetrance (1%)
•Potential of paternal occupational exposure (machinists, welders, motor vehicle mechanics, auto body repairmen)
RISK FACTORS:
•Aniridia (600 times greater than normal risk)
•Hemihypertrophy (100 times greater than normal risk)
•Cryptorchidism
•Hypospadias
•Duplicated renal collecting systems
•Wiedemann-Beckwith syndrome
•Drash's syndrome
•Klippel-Trenaunay syndrome
•Familial occurrence
•Paternal occupation (see Causes)
DIAGNOSIS
DIFFERENTIAL DIAGNOSIS:
•Neuroblastoma
•Hepatic tumors
•Sarcoma
•Rhabdoid tumors
LABORATORY:
•Urinalysis (occasional hematuria)
•CBC (anemia)
•LDH
•Plasma renin (rarely helpful)
•Urine catecholamines
PATHOLOGICAL FINDINGS:
•Favorable findings (mortality of 7%)
•Bulky lesion, well-encapsulated
•Focal areas of hemorrhage and necrosis
•Absence of anaplasia and sarcomatous cell types
•Presence of blastema, stomal and epithelial elements
•Unfavorable histology (mortality rate of 57%)
•Anaplasia - markedly enlarged and multipolar mitotic figures 3-fold enlargement of nuclei in comparison with adjacent similar nuclei, hyperchromasia of enlarge nuclei. Anaplasia may be diffuse or focal.
•Sarcomatous changes - are now considered to be separate from Wilms, not subtypes. (Mortality of 64%)
•Nephroblastomatosis
•Considered premalignant
IMAGING:
•Chest x-ray
•KUB (presence of linear calcifications)
•Abdominal ultrasound - gives best information about tumor extension into IVC
•CT (with IV and oral contrast) of chest and abdomen
•IVP rarely helpful
DIAGNOSTIC PROCEDURES:
Occasionally bone marrow aspiration necessary to distinguish from neuroblastoma
TREATMENT
APPROPRIATE HEALTH CARE:
•In-patient work-up and treatment until stable postoperative and induction chemotherapy completed
GENERAL MEASURES:
•Chemotherapy
•Radiation therapy in Stage II, unfavorable histology, Stage II and Stage IV
SURGICAL MEASURES:
•Examination (visual and manual) of contralateral kidney
•Radical nephroureterectomy and biopsies as needed to provide precise staging information
•Sampling of any enlarged lymph nodes
•Identification of any retained tumor with titanium clips.
•Tumor should be given to pathologist fresh, not on formalin
•Vertical midline incision if tumor extension to right atrium present (possible use of cardiopulmonary bypass)
•With bilateral Wilms' tumors, biopsy, then chemotherapy and 2nd look operation 6 weeks to 6 month later for partial bilateral nephrectomy if possible
PATIENT EDUCATION:
•Patient and family teaching regarding long-term outlook
•Possibility of second malignancy
•Side effects of chemotherapy, radiation therapy
MEDICATIONS
DRUG(S) OF CHOICE:
•Dactinomycin (actinomycin-D)
•Vincristine
•Doxorubicin
•Cyclophosphamide (Cytoxan)
Contraindications: Refer to manufacturer's literature
Precautions: Refer to manufacturer's literature
Significant possible interactions: Refer to manufacturer's literature
ALTERNATIVE DRUGS:
•Doxorubicin (Adriamycin)
•Cyclophosphamide
FOLLOW UP
PATIENT MONITORING:
•Multidrug chemotherapy every 3-4 weeks for 16 weeks - 15 months depending on stage
•Every 4 months for 1 year, every 6 months for 2nd - 3rd year, yearly after that
•CBC, CT chest and abdomen with each visit
POSSIBLE COMPLICATIONS:
•1-2% will develop second malignant neoplasms (leukemia, lymphoma, hepatocellular carcinoma, soft tissue sarcoma)
•High risk of low birth weight infants, perinatal mortality in offspring of female survivors of Wilms' tumor
•Chest is usual site of recurrence
EXPECTED COURSE AND PROGNOSIS:
•With favorable histology, 91% survival
•With diffuse anaplasia, 20% survival
•With focal anaplasia, 64% survival
•With rhabdoid features, 19% 3 year survival
•Staging
•I - tumor limited to kidney, completely excised
•II - Tumor extends beyond kidney, completely excised
•III - Residual non-hematogenous tumor confined to abdomen (lymph nodes positive, spillage of tumor, peritoneal implants, extension beyond resection region)
•IV - Hematogenous metastases
•V - Bilateral renal involvement
REFERENCES
•Ashcraft KW, Holder TM: Pediatric Surgery. 2nd Ed. Philadelphia, W.B. Saunders Co., 1993
•Shochat SJ: Wilms' Tumor: Diagnosis and Treatment in the 1990's. Seminars in Pediatric Surgery 1993;2(1):59-68
•O'Neill JA, Rowe MI, Grosfeld JL, et al: Pediatric Surgery. 5th ed., St Louis, Mosby, 1998 |
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