Symptoms and diagnosis of Wilms' tumor

The most common symptom of Wilms tumor in children is the asymptomatic appearance of a palpable tumor (61.6%). Often, the tumor is detected during examination of a child in the absence of any complaints (9.2%). In addition, macrohematuria (15.1%), constipation (4 3% weight loss (3.8%), urinary infection (3.2%), and diarrhea (3.2%) are possible. Rarely described symptoms of Wilms tumor in children are nausea, vomiting, pain, the appearance of an abdominal hernia with a large tumor, and increased blood pressure.

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Diagnosis of Wilms' tumor

Evaluation of a child with suspected Wilms tumor should include laboratory tests and radiologic studies.

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Laboratory diagnostics of Wilms tumor

• Complete blood count;
• biochemical blood test, including determination of the concentration of creatinine, urea, electrolytes and calcium in the blood serum;
• evaluation of coagulogram;
• general urine analysis;
• Cytogenetic study to detect deletion of 11p13 in WAGR syndrome, duplication of the paternal allele of 11p15 in Beckwith-Wiedemann syndrome, mutation of the WT1 gene in Denys-Drash syndrome.

Instrumental diagnostics of Wilms tumor

• Ultrasound of the kidneys, renal vessels, inferior vena cava, abdominal organs.
• CT scan of the abdomen and chest.
• CT of the abdominal cavity will help to clarify the organ affiliation of the tumor, the condition of the lymph nodes of the retroperitoneal space and abdominal cavity, the contralateral kidney (for bilateral lesions), the renal and inferior vena cava (for tumor venous thrombosis) and the liver (to exclude metastases).
• CT scan of the chest cavity (if CT scan reveals focal lung lesions that are not detectable on radiography, a biopsy of the nodular lesions should be recommended).
• X-ray of the lungs (4 fields) aimed at identifying metastases (patients with metastases to the lungs, visualized by X-ray, are shown irradiation of all lungs).

Histologic confirmation of the diagnosis of Wilms tumor is mandatory. In North America, patients with suspected Wilms tumor undergo immediate nephrectomy with regional lymph node biopsy according to the clinical programs of the National Wilms Tumor Study Group. Regional lymph node dissection is not a mandatory standard, but some investigators routinely remove regional lymph nodes in all patients. In North America, immediate nephrectomy is performed only in patients with bilateral tumors. In contrast, most European centers establish a clinical diagnosis based on imaging data alone. Clinical centers in Europe that are members of the International Society of Pediatric Oncology (SIOP) administer chemotherapy to all patients before nephrectomy.

Percutaneous biopsy is not indicated to verify the diagnosis, as it can lead to the development of undesirable complications and aggravate the course of the disease.

Patients with negative chest X-ray and positive CT results require biopsy of focal lesions and confirmation of their metastatic nature, since pathological changes in lung tissue (histoplasmosis, atelectasis, pseudotumors, intrapulmonary lymph nodes, pneumonia) can stimulate metastases of Wilms tumor to the lungs.

The main diagnostic signs of Wilms' tumor in children are a non-homogeneous or solid tumor of the kidney with cystic inclusions and hypodense zones, the tumor has a clear outline without signs of infiltration of surrounding tissues. Destruction, deformation and displacement of the calyces and pelvis are characteristic. With intravenous bolus contrast, an increase in the non-homogeneity of the tumor structure is noted in CT and MRI. Signs of hemorrhage into the tumor are common (27% of observations). On the contrary, calcifications are detected extremely rarely (about 8% of observations).

Differential diagnosis of Wilms tumor

In children, it is necessary to differentiate Wilms' tumor from neuroblastoma: in addition, a differential diagnosis is carried out with lymphoma, teratoma, cystic nephroma, hamartoma, hematoma, renal carbuncle, and xanthogranulomatous pyelonephritis.

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Complications of Wilms' tumor

The incidence of postoperative complications is 12.7%. The most common complications of Wilms tumor are small bowel obstruction (5.1%), bleeding (1.9%), and wound suppuration (1.9%). Additional treatment after nephrectomy may result in damage to some organs (heart, lungs, liver, bones, gonads). Both chemotherapy and radiation therapy may induce the development of secondary tumors.

Chronic renal failure in patients treated for Wilms tumor is rare. Its development is facilitated by the removal of functioning renal parenchyma, as well as postoperative irradiation.

Congestive heart failure may result from the administration of tetracyclines, requiring cardiac monitoring in patients receiving doxorubicin.

Obtaining lungs from patients with pulmonary metastases may be complicated by the development of pneumosclerosis and respiratory failure. The total and vital capacity of the lungs after irradiation may decrease by 50-70% of the initial

Hepatotoxicity of Wilms tumor treatment is caused by two factors: radiation and dactinomycin administration. The incidence of liver function impairment is 2.8-14.3%. In some cases, acute hepatic vein thrombosis may develop, leading to the development of corresponding symptoms.

Irradiation of the abdominal cavity leads to sclerotic changes in the sex glands and, as a consequence, to a decrease in fertility after reaching reproductive age. The development of hormonal insufficiency of the sex glands is also facilitated by the use of alkylating drugs.

Abdominal irradiation is also associated with impaired bone growth, particularly of the spine, which causes the development of scoliosis.

Chemotherapy, including doxorubicin, dactinomycin and vincristine, as well as radiation, increase the risk of developing secondary malignancies. After 15 years from diagnosis, the probability of developing a secondary tumor is 1.6°/ Treatment of recurrent Wilms tumor increases this figure by 4-5 times.

The most common localization of relapses is the lungs. In addition, damage to the bed of the removed kidney is possible (1/4 of relapses).

Bones and brain are common sites of recurrence in patients with favorable histological tumor variants.

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