Ultrasound Pictures “Fibrolamellar Hepatocellular Carcinoma”

                 Radiology imaging Fibrolamellar hepatocellular carcinoma (FLC) is an uncommon tumor with clinical and pathological features different from those of hepatocellular carcinoma.

                  This neoplasm occurs predominantly in young adult patients, who have no history of cirrhosis or chronic liver disease.

Macroscopically, tumor size varies from 5 to 20 cm. The appearance of FLC is somewhat similar to that of focal nodular hyperplasia, with a central scar and multiple fibrous septa. Although hemorrhage is rare in FLC, necrosis and coarse calcifications have been reported in 20 to 60% of cases, especially in the central scar.

Most commonly, FLC is present as a solitary mass, although sometimes it may appear as bi-lobed or as a mass with small peripheral satellite lesions. Only rarely is FLC present as a diffuse multifocal mass. FLC lesions are usually intrahepatic, although sometimes pedunculated neoplasms may be found.

Histologically, FLC is composed of sheets of large polygonal tumor cells separated by abundant collagen bundles arranged in parallel lamellae. The tumor cells have a cytoplasm that is deeply eosinophilic and granular due to the presence of mitochondria. Sometimes FLCs contain bile.

The clinical presentation is variable, although patients commonly have abdominal pain, hepatomegaly, a palpable right upper quadrant abdominal mass, and cachexia, Less frequently, the disease is accompanied by pain and fever, which simulates a liver abscess, gynecomastia in men, venous thrombosis, or jaundice. The gynecomastia is a result of the conversion of circulating androgens into estrogens by the enzyme aromatase, which is produced by the malignant hepatocytes.

Venous thrombosis can occur due to invasion of the hepatic venous system or the inferior caval vein. Alternatively, it may form part of a paraneoplastic syndrome (Trousseau syndrome). Jaundice is a very rare condition, and can be caused either by invasion or compression of the biliary vessels by the tumor or by compression of the biliary vessels by enlarged lymph nodes.

The echostructure of this neoplasm is variable on US scans. Often the tumor contains both hyperand iso-echogenic components, and thus is not homogeneous. The central scar, when present, is frequently seen as a central area of hyperechogenicity.

On unenhanced CT images, FLC is usually seen as hypoattenuating compared to the liver and as well-defined with lobulated margins. Areas of lowdensity within the tumor correspond to the central scar or to necrosis and hemorrhage,while calcification may be seen in 15 to 30% of all central scars. During the arterial and portal-venous phases after contrast material administration, FLC is predominantly, but heterogeneously, hyperattenuating.

radiology imaging on ultrasound Fibrolamellar carcinoma on US. Ultrasound reveals a heterogeneous hyper- to isoechoic lesion (arrows) with a hyperechoic central area (arrowhead) that corresponds to the central scar.

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