Hepatocellular Carcinoma

HCC is the second most common malignant liver tumor of infancy. Whereas hepatoblastoma typically occurs in children under five years of age,

HCC demonstrates two peak periods of onset, one between four and five years of age and the other between 12 and 14 years of age [74]. Etiological and predisposing factors for HCC include glycogenosis types I, III, IV, VI and IX, galac-tosemia, thyroxinosis, biliary cirrhosis secondary to atresia of the bile ducts, and hepatitis B or C viral infection. The incidence of HCC is slightly greater among boys [34,90].

Histologically, pediatric HCC is composed of cells with an increased volume, a polygonal shape, abundant granules, acidophilic and glycogen-rich cytoplasm and an acidophilic nucleolus. The histo-logical features are similar to those described for HCC in adult subjects (see Chapt. 6, "Imaging of Malignant Focal Liver Lesions", section 6.1.^"Hepatocellular Carcinoma").

A variety of substances, such as Mallory bodies, AFP and a-1-antitrypsin, can be produced by the neoplastic hepatocytes. Adipose and glycogenic components may also be detectable in the cell cytoplasm. If the adipose component is abundant, the tumor is referred to as a hepatic clear cell carcinoma [51,83].

Macroscopically, three different growth patterns may be observed. The lesion may be a massive solitary mass which may or may not be encapsulated. The multifocal variant is characterized by the presence of numerous distinct, sometimes confluent nodules that can simulate metastases. Finally, the less common diffuse form can involve the whole liver and is characterized by multiple small neo-plastic foci that mimic the regeneration nodules of cirrhosis. Necrosis is sometimes extensive and can lead to the formation of cysts. HCC is defined as encapsulated when it is contained in a peripheral ring composed of fibrous tissue [29,34,58,61].

At diagnosis, the most common clinical symptoms and signs are anorexia, fever, abdominal pain,

Fig. 12a-h. Hepatoblastoma in a 2 year old girl. A slightly hyperintense lesion compared with the surrounding liver tissue can be seen on the unenhanced T2-weighted image (a). On the unenhanced Tl-weighted image (b), the lesion is revealed as a giant inhomogeneous hypointense mass with small areas of hyperintensity indicative of hemorrhage. The unenhanced Tl-weighted fat-suppressed image (c) more clearly reveals the areas of high SI (arrows) indicative of hemorrhage and regressive changes. The lesion appears slightly hypointense in comparison to the normal liver parenchyma. On dynamic imaging after the bolus administration of Gd-BOPTA (d-g), the more ventrally located parts of the lesion show hypervascularity (arrows in d and e), whereas most of the remaining parts show only slightly inhomogeneous contrast agent uptake. Due to the mass effect of the lesion, inhomogeneous perfusion of the remaining liver tissue can also be noted (arrowheadin e). Tl-weighted fat-suppressed images acquired during the delayed hepatobiliary phase (h) reveal inhomogeneous uptake of Gd-BOPTA. The lesions have a multinodular appearance with hypointense areas indicative of regressive changes

Fig. 12a-h. Hepatoblastoma in a 2 year old girl. A slightly hyperintense lesion compared with the surrounding liver tissue can be seen on the unenhanced T2-weighted image (a). On the unenhanced Tl-weighted image (b), the lesion is revealed as a giant inhomogeneous hypointense mass with small areas of hyperintensity indicative of hemorrhage. The unenhanced Tl-weighted fat-suppressed image (c) more clearly reveals the areas of high SI (arrows) indicative of hemorrhage and regressive changes. The lesion appears slightly hypointense in comparison to the normal liver parenchyma. On dynamic imaging after the bolus administration of Gd-BOPTA (d-g), the more ventrally located parts of the lesion show hypervascularity (arrows in d and e), whereas most of the remaining parts show only slightly inhomogeneous contrast agent uptake. Due to the mass effect of the lesion, inhomogeneous perfusion of the remaining liver tissue can also be noted (arrowheadin e). Tl-weighted fat-suppressed images acquired during the delayed hepatobiliary phase (h) reveal inhomogeneous uptake of Gd-BOPTA. The lesions have a multinodular appearance with hypointense areas indicative of regressive changes

Mri Images Liver Cancer

Fig. 13a-g. Hepatoblastoma in a 12 year old boy. Same case as shown in Fig. 9. On the unenhanced T2-weighted image (a), a slightly hyperintense lesion with retraction of the liver capsule is visible. The lesion is heterogeneously hypointense on the corresponding Tl-weighted image (b) due to internal hemorrhage. The lesion shows strong enhancement in the arterial phase (c) of the dynamic study after contrast agent injection (Gd-BOPTA, 0.05 mmol/kg) with subsequent early wash-out in the portal-venous phase (d). The Tl-weighted fat-suppressed image in the equilibrium phase (e) reveals a heterogeneously hypointense lesion. The lesion is clearly hypointense on the Tl-weighted (f) and Tl-weighted fat-suppressed (g) images acquired during the hepatobiliary phase 1 h after administration of Gd-BOPTA. This indicates a tumor that does not possess functioning hepatocytes. Note the high SI of the bile ducts (arrows), which is indicative of the hepatobiliary excretion of Gd-BOPTA

Fig. 13a-g. Hepatoblastoma in a 12 year old boy. Same case as shown in Fig. 9. On the unenhanced T2-weighted image (a), a slightly hyperintense lesion with retraction of the liver capsule is visible. The lesion is heterogeneously hypointense on the corresponding Tl-weighted image (b) due to internal hemorrhage. The lesion shows strong enhancement in the arterial phase (c) of the dynamic study after contrast agent injection (Gd-BOPTA, 0.05 mmol/kg) with subsequent early wash-out in the portal-venous phase (d). The Tl-weighted fat-suppressed image in the equilibrium phase (e) reveals a heterogeneously hypointense lesion. The lesion is clearly hypointense on the Tl-weighted (f) and Tl-weighted fat-suppressed (g) images acquired during the hepatobiliary phase 1 h after administration of Gd-BOPTA. This indicates a tumor that does not possess functioning hepatocytes. Note the high SI of the bile ducts (arrows), which is indicative of the hepatobiliary excretion of Gd-BOPTA

jaundice, and hepatomegaly; at times, its onset can be violent and sudden, with acute abdominal pain and hemoperitoneum due to rupture of the tumor or to rupture or erosion of the superficial vessels. The AFP values are high in more than 50% of cases and generally exceed 1000 ng/mL [7,34,89].

The prognosis for HCC is worse than that for HB, with a survival rate between 15% and 30%. This is due primarily to the large number of cases in which the cancer is multifocal or unresectable [89].

The appearance of HCC on US, CT and MR imaging is described in Chapter 6,"Imaging of Malignant Focal Liver Lesions", section 6.1.1,"Hepato-cellular Carcinoma".

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