CHAPTER 36 Hepatic Tumors
Step1: Surgical Anatomy
♦ The typical benign tumors of the liver that require resection are mesenchymal hamartoma, adenoma, and focal nodular hyperplasia. Hepatoblastoma is the most common malignant liver tumor of childhood; it usually occurs within the first 3 years of life. Hepatocellular carcinoma, sarcoma, and epithelioid hemangioendothelioma, a low- to intermediate-grade malignant tumor, is less common and generally is seen in older children.
♦ The liver is separated into nine anatomic segments, each with an independent portal venous and arterial inflow and biliary and hepatic venous drainage. This segmental anatomy forms the basis for the design and implementation of a successful anatomic resection of the liver (Fig. 36-1).
♦ The hepatic veins divide the liver into four sections: right anterior and posterior, left medial, and lateral. The left and middle hepatic veins form a common trunk before entering the vena cava in 60% of patients.
♦ The right hepatic artery and portal vein enter the liver parenchyma shortly after branching. The left hepatic duct and left portal vein have a longer course after branching. Together they course to the base of the umbilical fissure, where they join the left hepatic artery before entering the liver parenchyma (Fig. 36-2).
Step 2: Preoperative Considerations
♦ In the case of malignant lesions, most commonly hepatoblastoma, there should be an expectation of paired inflow and outflow structures that remain intact with an adequate resection margin. In most of these cases, the resection will be anatomic (i.e., along one of the planes outlined by the hepatic veins). Ligation of the appropriate arterial and portal venous inflow produces a demarcation line that correlates with the safe line of division. Benign lesions, in many situations, can be resected along nonanatomic lines.
♦ Cross-sectional imaging for evaluation the tumor and its relationship to the vasculature of the liver is the key to preoperative planning. This imaging can be a computed tomography scan or a magnetic resonance imaging. The use of ultrasound with duplex scanning can be helpful for evaluation of both portal and hepatic venous anatomy, and it can be used intraoperatively as well. Good-quality imaging studies should identify replaced or accessory arterial anatomy and the presence of an accessory right hepatic vein.
♦ Routine laboratory evaluation including blood count and renal panel would be expected, especially for children who are between rounds of chemotherapy, to ensure bone marrow recovery. Blood should be available for the procedure. Prophylactic parenteral antibiotics are given within 30 minutes of incision time and as appropriate throughout the length of the procedure.
♦ There is definite user preference for selected equipment, but certain types of equipment can improve exposure and minimize blood loss.
A mechanical retractor such as a Thompson retractor (Thompson Surgical Instruments, Inc.) or a Buchwalter will simplify exposure, especially for suprahepatic vena cava and right hepatic resections.
The ultrasonic dissector, water-jet dissector, electrocautery, and the argon-beam coagulator can all be useful during the parenchyma dissection. The dissectors can assist in exposure of the vessels and ducts within the substance of the liver so that these structures can be easily identified and ligated.
A mechanical retractor such as a Thompson retractor (Thompson Surgical Instruments, Inc.) or a Buchwalter will simplify exposure, especially for suprahepatic vena cava and right hepatic resections. The ultrasonic dissector, water-jet dissector, electrocautery, and the argon-beam coagulator can all be useful during the parenchyma dissection. The dissectors can assist in exposure of the vessels and ducts within the substance of the liver so that these structures can be easily identified and ligated.
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