Nephroblastoma is one of the most common renal pediatric solid tumors. It has a strong tendency of extension of the tumor thrombus along to the renal vein, the inferior vena cava, and the right atrium. We report the case of a 02 years and 08 months-year-old child, who received 8 chemotherapy doses for a left kidney nephroblastoma invading the left renal vein and inferior vena cava. Two months later, the tumor size decreased and measured 13 X 10 cm but the vascular thrombus persisted. So, he underwent left nephrectomy and the removal of the intravascular tumoral thrombus under median laparotomy and cavotomy. The postoperative CT scan showed a small hematoma and a thrombosis of the infrarenal vena cava. So, we decided to continue curative anticoagulant therapy for 3 months. Surgical management of nephroblastoma with vascular extension remains a significant challenge. Intravascular extension must be well characterized in all patients in order to indicate preoperative chemotherapy and guide resection approach.

Nephroblastoma, also known as Wilms tumor, is one of the most common renal pediatric solid tumors. It has an incidence estimated at 6% of pediatric tumors, it accounts for more than 90% of all childhood kidney tumors (1). It has a strong tendency to invade nearby vessels in the form of a thrombus. In fact, extension of tumor thrombus along to the renal vein into the inferior vena cava occurs in 4-10% of all patients. Tumor thrombus extending to the right atrium is less reported as 0.7-1 Intravascular thrombus occurs in 20–35% of patients, while extension to the IVC ranges from 4 to10% [1,2]. A thrombus reaching the atrium is a more rare event and occurs in less than 1% of all patients [3].

Treatment consists especially on preoperative chemotherapy and surgical excision, and needs multidisciplinary care involving oncologists, pediatric surgeons, and vascular surgeons [4]. We report the case of a 02 years and 08 month-year-old child, who was treated for a left kidney nephroblastoma invading the left renal vein and inferior vena cava, who underwent surgery to remove the left kidney and the intravascular tumoral thrombus.

Nephroblastoma is the most common abdominal pediatric tumor. It is a malignant embryonic tumor that develops from the mesoderm of the intermediate cell mass before differentiation. It typically presents between ages 3 to 5 years but can also be seen in new born infants [5]. Clinical presentation is usually made of an asymptomatic abdominal mass in the majority of children. However, abdominal pain, hematuria, urinary tract infections, varicocele and hypertension or hypotension can be seen. The most common initial presenting symptom is abdominal pain (30% to 40%) followed by high blood pressure (25%), and hematuria (12% to 25%) [6].

Treatment of Wilms tumor without vascular involvement is nephrectomy in majority of cases followed by chemotherapy. There are other protocols that start with chemotherapy first and perform the nephrectomy later. Lymph nodes clearance is very important for staging and to improve general survival [6]. Intravascular extension into renal vein then the vena cava occurs in only 4-10% of patients. It is reported that intravascular extension when Wilms’ tumor is located in the right kidney is more common due to the shorter renal vein. It is also reported that vascular involvement is more frequent in older children with a mean age of 3.75 years than younger children [7].

Several classifications for vascular extension were established in the past. Daum’s classification that was established in 1994 [8] was the most used classification until 2013, when Abdullah et al [9] proposed a modification of Daum’s classification and suggested the addition of a fifth stage for intraventricular extension of the vascular thrombus. The importance of this stage is mainly in anesthetic management. Positive pressure ventilation may cause tricuspid valve immediate cardiac arrest [7].

Figure 5: control CT scan showing the presence of a small hematoma and a thrombosis of the inferior vena cava.

The operative approach of Wilms’ tumor with intravascular extension represents a constant challenge, and the surgeons should have an appropriate experience level. Extension below the hepatic veins can be approached via a laparotomy. However, proximal extension above the hepatic veins requires the same incision extended to median sternotomy [7]. The post-operative outcomes are influenced by intravascular extension [10-12], with an odds ratio of 2.2 for complications when intravascular thrombus is present. There was also an association between decrease in surgical complication’s rate and the administration of neoadjuvant chemotherapy [13]. It’s interesting to know that survival rates do not differ from those with uncomplicated Wilms’ tumor [14].

The prognosis depends on the tumor stage and histology. Favourable histology has a better survival rates, it’s estimated at 86% to 99%, while unfavorable histology survival varies from 38% to 84% depending on the stage [15-18]. Recurrence risk is estimated at 15%, it’s mainly found within the first 2 years after surgery [6].

Surgical management of Wilms’ tumor with vascular extension remains a significant challenge. Intravascular extension must be well characterized in all patients in order to indicate preoperative chemotherapy and guide resection approach. The surgical team should be multidisciplinary involving pediatric and vascular surgeons and should have an appropriate experience level.

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