[Imaging findings of fibrolamellar hepatocellular carcinoma]

To describe the imaging findings of fibrolamellar hepatocellular carcinoma(FL-HCC).

Imaging studies in 11 patients with pathologically confimed F1-HCC were reviewed. There was no cirrhosis or hepatitis according to patients' history. Serum alpha-fetoprotein level was normal in all patients. Imaging studies included ultrasonography(US) in 10 patients, CT in 11, MRI in 8, and angiography in 9.

(1) On US, the echogenicity of the tumor was hyperechoic relative to normal liver in four patients, and mixed in six. Cyst-like regions with various sizes were found within the masses in four patients, Doppler US revealed that the solid portion of the tumor was hypervascullar. (2) Nonenhanced CT scan demonstrated a well demarcated, solitary mass in 9 patients, and a multilobulated mass in 2. All masses were non-homogeneous and hypodense to the liver. Seven of the lesions had a central lower density region with radiating pattern which was confirmed as densely packed scar by pathologic examination. Punctate calcification was seen in 4 of 11 patients. Marked contrast enhancement of the masses was seen on the arterial dominated phase in 7 patients under enhanced CT, and a central nonenhanceing scar-like structure was found in 4 of the seven patients, Liver cirrhosis and splenomegaly were not found in this series. (3) On MRI, the tumor was hypointense relative to the liver parenchyma on T1-weighted spin-echo image and non-homogeneous hyperintense on T2-weighted image. Six of the eight patients had a central radiate-like structures which were hypointense on both T1 and T2-weighted images. On contrast enhanced MRI, four of five patients had obvious enhancement, and the central scar did not enhance on both early and delayed enhancement. (4) On angiography, a globular hypervascular mass with neovascularity was found in four of the nine patients. Peripheral nodular tumor stain, which was similar to that of hemangioma, was seen in 3 patients. A hypovascular mass with displacement of the adjacent vessels was found in 2 cases. No tumor thrombus in the portal vein, nor arterial shunting to the portal vein was identified.

Typical imaging features in young patients of a large hepatic mass with central scar and calcification but without cirrhosis might be suggestive of FL-HCC.