gastrointestinal tract and abdomen TUMORS OF THE LIVER AND BILIARY TRACT Gabriela M. Vargas, MD, Purvi Parikh, MD, FACS, and Kimberly M. Brown, MD, FACS* Liver Tumors portion of the liver that is separate from the right and left hemilivers, is also referred to as segment 1. The left lateral anatomic considerations section comprises segments 2 and 3; the left medial section A necessary prerequisite to the discussion of liver tumors comprises segment 4 (which is sometimes further divided and their treatment is a clear understanding of internal liver into segments 4a and 4b); the right anterior section com- anatomy and a common point of reference for the terminol- prises segments 5 and 8; and the right posterior section ogy used in describing liver resections. In 2000, the Ameri- comprises segments 6 and 7. cas Hepato-Pancreato-Biliary Association (AHPBA) and the Following this terminology, one describes a hepatic re- International Hepato-Pancreato-Biliary Association (IHPBA) section or ablation by the anatomic portions of the liver presented the work of the AHPBA/IHPBA Ter minology involved [see Table 1]. Resection or ablation of a lesion that Committee at the annual meeting in Brisbane, Australia. The involves less than a segment would reference the segment results of this work to stand ardize terminology for descrip- in which the lesion is located. Resection of an anatomic tions of hepatic anatomy and resections have been widely segment would be described as a segmentectomy of the ap- accepted as standard nomenclature.1 p ropriate segment. Resection of segments 2 and 3, 4a and 4b, The basis for the Brisbane terminology is that the internal 5 and 8, or 6 and 7 would be termed a sectionectomy. Re- vascular and biliary anatomy determines the anatomic divi- section of segments 2 to 4 is a “left hepatectomy” or “left sions rather than surface markings [see Figure 1]. The he patic hemihepatectomy,” whereas resection of segments 5 to 8 artery and bile duct follow a similar pattern of branching, is a “right hepatectomy” or “right hemihepatectomy.” If the whereas the portal vein branching on the left side has a caudate lobe is resected with the hemihepatectomy, that variation due to the fetal umbilical vein traveling from the should be noted. Resections involving more than the ana- umbilical cord to the left portal vein. The postnatal remnant tomic hemiliver are referred to as “extended right hemi- of this structure (round ligament) carries blood away from hepatectomy” or “extended left hemihepatectomy,” with the liver. specifi cation of which additional segments were removed. The fi rst-order division of the proper hepatic artery and The terms right trisectionectomy and left trisectionectomy are the common hepatic duct into the right and left hepatic also appropriate. arteries and right and left hepatic ducts, respectively, results in division of the liver into two parts, referred to as the right primary liver cancers and left hemilivers (or the right and left livers) [see Figure 1 Hepatocellular Carcinoma and Table 1]. In this system of terminology, the term lobe is never used to denote a hemiliver, because it bears no rela- Hepatocellular carcinoma (HCC), also termed hepatoma, tion to the internal vascular anatomy. The plane between is the most common primary liver cancer worldwide. It is these two zones of vascular supply is called a watershed. seen more frequently in men than in women. HCC develops The border watershed of the fi rst-order division is a plane in the background of chronic liver disease, which has pro- that intersects the gallbladder fossa and the fossa for the gressed from acute liver injury to fi brosis to cirrhosis and, 2 inferior vena cava and is called the midplane of the liver. ultimately, carcinoma. In sub-Saharan Africa and Southeast The second-order division divides each of the hemilivers Asia, where HCC is more prevalent than in the Western into two parts, referred to as sections. The right hemiliver Hemisphere and Europe, hepatitis B virus (HBV) infection is comprises the right anterior section and the right posterior responsible for most cases. In the United States, HCC age- section. These sections are supplied by a right anterior adjusted incidence rates have doubled in the last decades.3 sectional artery and a right posterior sectional artery and are The rise in incidence has been linked to a concomitant rise drained by a right anterior sectional hepatic duct and a right in hepatitis C virus infection.4 Other important risk factors posterior sectional hepatic duct. The left hemiliver compris- in the development of cirrhosis and subsequently HCC es the left medial section and the left lateral section. These include alcoholism, afl atoxin B1 exposure, a1-antitrypsin sections are supplied by a left medial sectional hepatic artery defi ciency, obesity, hemochromatosis, primary biliary and a left lateral sectional hepatic artery and are drained cirrhosis, and nonalcoholic steatohepatitis (NASH). by a left medial sectional hepatic duct and a left lateral sectional hepatic duct. Clinical presentation HCC typically presents with non- The third-order division divides the liver into nine seg- specifi c symptoms such as abdominal pain, weight loss, ments, each of which has its own segmental artery and bile anorexia, jaundice, and malaise. Physical examination fi nd- duct [see Figure 1 and Table 1]. The caudate lobe, a unique ings may include hepatomegaly and ascites. In a patient with known liver disease, HCC often presents as an acute * The authors and editors gratefully acknowledge the contribu- deterioration of previously stable liver function, including tions of the previous authors, Steven M. Strasberg, MD, FACS, the appearance of ascites, encephalopathy, or jaundice. FRCSC, FRCS(Ed), and David C. Linehan, MD, FACS, to the Screening high-risk individuals for HCC can reduce development and writing of this chapter. mortality from HCC.5 Serum a-fetoprotein (AFP) testing and Scientific American Surgery © 2014 Decker Intellectual Properties Inc DOI 10.2310/7800.2250 01/14 gastro tumors of the liver and biliary tract — 2 Right Hemiliver (Right Liver) Left Hemiliver (Left Liver) Inferior Vena Cava Middle Hepatic Vein Right Hepatic Vein Left Hepatic Vein 2 8 1 7 3 4 Falciform Ligament 5 Portal Vein 6 Common Hepatic Artery Common Bile Duct Right Posterior Right Anterior Left Medial Left Lateral Section Section Section Section Figure 1 Anatomic divisions of the liver according to the International Hepato-Pancreato-Biliary Association and the Americas Hepato- Pancreato-Biliary Association (IHPBA/AHPBA)-sanctioned terminology, including fi rst-order divisions (hemilivers), second-order divisions (sections), and third-order divisions (segments). Each segment has a numeric designation. Segments 2, 3 and 4 comprise the left hemiliver, segments 5–8 comprise the right hemiliver, and segment 1 is also referred to as the caudate lobe. ultrasonography (US) are the two most widely employed 20 mm may be diagnosed by imaging with a specifi city of screening strategies. Screening should be performed in a greater than 99%.6 To properly diagnose HCC radiographi- setting with standardized processes for follow-up of results cally and distinguish HCC from other tumors, such as chol- and quality control procedures, particularly given the angiocarcinoma, a four-phase study (CT or MRI) is required: operator dependence of US. Current guidelines recommend unenhanced, arterial, venous, and delayed phases. On US, US and AFP testing every 6 to 12 months for patients with most nodules will appear hypoechoic, but lesions may also cirrhosis of viral or nonviral etiology and HBV carriers with- appear as isoechoic, as hyperechoic, or of mixed echogenici- out cirrhosis. In addition, patients with HBV or hepatitis C ty. Contrast-enhanced US has fallen out of favor as a diag- virus (HCV)-associated cirrhosis should be referred to a nostic tool.7 Currently, positron emission tomography (PET) hepatologist for treatment of the viral hepatitis as treatment has no role in the diagnosis of HCC.8 Patients with lesions can improve HCC outcomes in these patients. exhibiting characteristic features for HCC, or with an elevat- ed AFP, do not require a biopsy. An algorithm for the Diagnostic studies HCCs are hypervascular lesions management of suspicious liver nodules is summarized in whose blood supply is primarily from the hepatic artery; Figure 3 [see Figure 3]. therefore, on multidetector computed tomographic (CT) imaging, the lesion typically appears hyperintense during Staging Preoperative staging for HCC requires assess- the arterial phase and hypodense (referred to as “washout”) ment of tumor extent and the degree of underlying liver during the delayed phases [see Figure 2].6 Magnetic reso- dysfunction. A high-quality multiphase cross-sectional nance imaging (MRI) is more sensitive than CT for the imaging study of the abdomen is performed to assess the detection of HCC. On T2-weighted MRIs, the lesion usually size, location, and number of liver tumors, as well as any appears hyperintense; whereas its appearance is variable evidence of extrahepatic disease. CT of the chest is indicated on T1-weighted images. Up to 60 to 70% of HCCs of 10 to to exclude lung metastases. Bone scans are reserved for Scientific American Surgery 01/14 gastro tumors of the liver and biliary tract — 3 Table 1 Brisbane 2000 Terminology for Hepatic Anatomy and Resections from the IHPBA Level of Preferred Anatomic Corresponding Division Term Couinaud Segments Preferred Term for Surgical