Nephroblastoma

Nephroblastoma, also referred to as Wilms tumor, is the fifth most common malignancy in childhood and the most frequent renal tumor in the pediatric population [1] [2]. Additionally, its peak incidence is in early childhood between the ages of 3 to 4 [3]. Patients with trisomies 13 and 18, Beckwith-Wiedemann syndrome, and Drash syndrome are at risk for developing this tumor [3]. Due to advances in treatment, the survival rate is 80% to 90%.

Regarding the presentation, the majority of patients will have an asymptomatic abdominal mass [4] [5] while some will also develop manifestations such as malaise, abdominal pain, hematuria, and hypertension [5]. The mass may be discovered incidentally or during a workup following trauma, hematuria, or hypertension [4]. In rare cases, the tumor ruptures and causes fever, pain, and anemia [5]. Furthermore, respiratory symptoms are present in those with metastasis to the lungs.

Nephroblastoma adheres to the "rules of 10s," which relates that 10% of these cases are bilateral, 10% develop vascular invasion, 10% exhibit lung metastasis at initial presentation, 10% have histology suggestive of poor outcome, and 10% demonstrate calcifications on imaging [6].

Complications

There are adverse effects associated with various types of treatment. For example, radiation therapy poses danger to the remaining kidney while chemotherapy agents are harmful to the liver and other organs. Also, removal of one kidney will lead t0 hypertrophy of the remaining kidney.

Physical exam

Remarkable findings include an abdominal mass, which should be palpated carefully to avoid rupture. Other notable features will be those of associated syndromes.

Any child with an abdominal mass warrants a full workup consisting of a patient and family history, complete physical exam, and the appropriate studies.

Laboratory tests

The clinician must obtain a complete blood count (CBC), complete metabolic panel (CMP) including renal function tests, and a coagulation panel. Urinalysis is also important.

Cytogenetic testing

Chromosomal analysis for associated syndromes is indicated.

Imaging

Ultrasonography of the kidneys is the initial diagnostic modality since it is widely available, inexpensive, and safe. Renal ultrasonography determines the location and characteristic of the mass as it differentiates solid from cystic lesions [5]. This study also detects thrombi in the inferior vena cava (IVC).

Abdominal computed tomography (CT) scan provides critical details regarding the tumor's origin, vascular and lymph nodal invasion, bilateral renal involvement, and metastatic disease [7]. Moreover, CT with contrast enhancement demonstrates a greater sensitivity for vascular involvement [8].

Experts advocate that contrast-enhanced magnetic resonance imaging (MRI) is the preferred diagnostic study [3]. This modality exhibits the most sensitivity for ascertaining caval patency and invasion. Generally, a nephroblastoma has low signal intensity on a T1 weighted image and high intensity on T2 [9].

Chest radiography and CT scan are performed to investigate lung metastasis.

Histology

The diagnosis is confirmed by histologic analysis of the tumor, which is characterized by epithelial, stromal, and blastemal embryonic elements [4]. Very importantly, histology also determines the prognosis [10].

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10. Beckwith JB, Palmer NF. Histopathology and prognosis of Wilms tumor results from the first National Wilms’ Tumor Study. Cancer. 1978;41(5):1937–48.