Key words : Liver tumor, Pediatric liver transplant, Thrombosis

Introduction

Hepatoblastoma is the most common malignant liver tumor in children. In the case of hepatoblastoma with invasion into the portal vein (PV) or widespread thrombosis of the PV, tumor resection is impossible. Moreover, the only treatment method in such cases is liver transplant (LT). In pediatric recipients, LT with insufficient flow because of thrombosis or PV hypoplasia is a much more difficult procedure than in adult recipients. In most cases, pediatric LT is performed from an adult living donor, and typically the liver graft is undesirably large and receives insufficient blood flow into the graft due to the small diameter of the recipient PV. In such cases, there is a higher rate of complications, such as stenosis, thrombosis, and vessel torsion, resulting in liver graft dysfunction and loss. According to the literature, the incidence of PV complications in pediatric LT is common and ranges from 6% to 12%.^1-3

Various surgical methods have been developed and implemented to solve PV complications in children with fatty liver disease. Scientists in Japan have reported the effectiveness of vein graft interposition and collateral interruption in cases of PV hypoplasia or thrombosis.^4,5 Kasahara and colleagues developed a new technique for PV reconstruction using the so-called pull-out method for living donor LT in children with PV obstruction.⁶

A report from Korea described the introduction of a PV reconstruction method for LT in children using an end-to-side graft. Scientists presented a new end-to-end superior mesenteric vein graft technique during pediatric LT using a partial adult liver graft. The end-to-side retro pancreatic jump graft technique using an iliac vein graft for PV reconstruction has shown good results.⁷ Yi and colleagues have used the ellipsoid technique for reconstruction in patients with PV hypoplasia,⁸ with good results.

In cases of PV thrombosis associated with neoplastic liver lesions such as hepatoblastoma, it is important to calculate sufficient reserve for reconstruction. Therefore, we used part of the recipient’s external jugular vein to reconstruct the PV.

Case Report
Our center performed LT from a living donor to a child diagnosed with hepatoblastoma, a fetal epithelial variant without signs of metastasis. The recipient was a 5-year-old boy weighing 15 kg who had received a course of polychemotherapy. During examination, alpha-fetoprotein (AFP) reached 35172 IU/mL. After neoadjuvant chemotherapy, AFP decreased to 16 IU/mL. Ultrasonography of the abdominal cavity showed a space-occupying lesion in the right lobe of the liver, cavernous transformation of the PV, hepatosplenomegaly, and diffuse focal changes in the liver. Computed tomography of the abdomen showed liver tumor with signs of invasion into the inferior vena cava, cavernous transformation of the PV, hepatosplenomegaly, and dilatation of intrahepatic and extrahepatic bile ducts.

The child underwent a midline laparotomy under general anesthesia. At the hilum of the liver, we found an enlarged lymph node measuring 2.0 × 1.5 cm, from which biopsies were taken for pathohistological examination. Express biopsy did not reveal tumor cells in the lymph node. To maintain adequate perfusion, the upper and lower mesenteric veins were cannulated with an 8F catheter and achieved satisfactory extracorporeal venous blood circulation. During the inspection, we observed developed collateral vessels in the hilum of the liver. Deep PV thrombosis was detected, and thromboendovenectomy of the inferior vena cava and PV was performed.

Orthotopic transplant was performed from a living donor (2 to 3 liver segments donated by the father of the recipient).. Considering the extensive diastasis of the recipient’s PV (after thrombectomy of the PV) and the left PV graft, we used a 4.5-cm segment of the recipient’s left internal jugular vein. The venous insert (autograft of the internal jugular vein) was connected to the area of confluence of the superior mesenteric vein and the PV of the recipient. The left PV of the hepatic graft was then anastomosed with the autovenous graft. The left hepatic artery was anastomosed with the recipient’s hepatic artery using an 8/0 polypropylene (Prolene) suture under a microscope. Baseline ultrasonography assessment of blood flow showed insufficient flow in the PV. To enhance blood flow in the collateral vessels, the dilated collateral veins of the left gastric vein were isolated and ligated. The autovenous insert was reanastomosed with the dilated collateral mesenteric vein. Sufficient portal flow was confirmed by ultrasonography. The bile ducts were connected to form a hepatojejunostomy on a Roux-en-Y (30 cm) loop. For immunosuppression therapy, the patient received glucocorticoids intravenously and tacrolimus (Prograf) orally.

In the early postoperative period, against the background of satisfactory liver graft function, we noted a decrease in liver transaminases, bilirubin, and AFP. A follow-up assessment with Doppler ultrasonography showed satisfactory blood flow in the vessels; the liver transplant showed no anomalous features.

Conclusions

Despite the pronounced vascular transformation of the PV with extensive thrombosis of the PV in the recipient, the use of a native vascular graft from the external jugular vein of the recipient himself to form a portoportal anastomosis was the optimal solution in such situations.

References:

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