Teaching Case

A 7-year male child presented with hematuria and swelling in the right lumbar region. Clinical examination revealed a palpable mass in the right lumbar region. Urine routine microscopy revealed few red blood cells. He had a haemoglobin of 9.5 g/L and a normal renal function and coagulation profile.

USG revealed a large solid cystic mass replacing the right kidney. A contrast-enhanced CT scan was done to characterize the mass, which showed that the kidney was almost entirely replaced by a large heterogeneously enhancing mass lesion measuring ~14.8 x 11.8 x 18.3 cm (AP x TR x CC). The mass was extending along the right renal pelvis and right ureter up to the right vesicoureteric junction (VUJ). The mass was crossing the midline and displacing and compressing the adjacent abdominal structures without infiltrating them. Renal artery, vein, and Inferior vena cava (IVC) were displaced and compressed anteriorly without intravascular extension. The patient underwent fine-needle aspiration and cytology (FNAC), which revealed a triphasic Wilms tumour.

Background

Wilms tumour is the most common childhood renal malignancy, and it represents approximately 7% of all pediatric malignancies [1]. WT1 and WT2 on chromosome 11  are responsible for the genesis of  of Wilms tumours [2]. An abnormal  WT1 gene is associated with WAGR syndrome (Wilms tumour, aniridia, genitourinary abnormalities, mental retardation) and Drash syndrome (male pseudohermaphroditism, progressive glomerulonephritis); an abnormal WT2 gene is associated with Beckwith-Wiedemann syndrome or hemihypertrophy. However, the development of Wilms tumour is multifactorial, and loci on chromosomes 1, 12, and 8 are also implicated in it’s genesis [2].

Clinical Perspective

 Wilms tumour, most commonly, presents clinically as a palpable mass. [3]. Hematuria and pain are rare presenting symptoms. There is usually an absence of Constitutional symptoms, but hypertension may be present due to renin production by the mass [3]. Sonography is the preliminary investigation and further characterization of the mass and the staging is done with either contrast-enhanced CT or MRI [1]. On CT, Wilms tumour is seen as heterogeneous attenuation mass and shows less enhancement than the normal renal parenchyma and usually shows infiltration into the renal vein and can extend further into the right atrium. Ureteric extension of Wilms tumour is rare, with an incidence rate of approximately 2% and only  0.4 %  of ureteric involvement shows extension up to VUJ and urinary bladder [4]. The clinical feature indicative of ureteric extension is gross hematuria, and therefore, the presence of hematuria should raise the alarm about the possibility of ureteric extension [4,5].

 Invasion of the ureteric wall consider as Stage II disease by The Société Internationale D`Oncologie Pédiatrique (SIOP) classification [6].  Preoperative knowledge of the ureteric extension of the tumour is necessary for en-bloc resection of the tumour. It is essential to prevent local spillage of the tumour by cutting across the tumour, which makes it a stage III disease[7].

Take-home points

Ureteric extension of Wilms tumour is rare, and the presence of hematuria should raise suspicion. It's essential to recognize it to avoid cutting across the tumour and causing a tumour spill.