Fibrolamellar hepatocellular carcinoma: multiphasic CT features of the primary tumor on pre-therapy CT and pattern of distant metastases.
Abdom Radiol (NY). 2018 Jun 13. doi: 10.1007/s00261-018-1657-2. [Epub ahead of print] Ganeshan D1, Szklaruk J2, Kaseb A3, Kattan A2, Elsayes KM2.
OBJECTIVE: The aim of our study is to describe the multiphasic CT features of fibrolamellar hepatocellular carcinomas (FLHCCs) and pattern of distant metastases.
MATERIALS AND METHODS: 33 patients (mean age 28 years: 17M/16F) with pathologically confirmed FLHCC and pre-treatment multiphasic CT were included in the study. Two abdominal radiologists evaluated the multiphasic CT imaging features of these 33 FLHCC patients in consensus.
RESULTS: Solitary hepatic mass was seen in 67% (22/33). Mean tumor size was 11.3 cm (range 4.6-22 cm). Tumor was well-defined in 64% (21/33). In the pre-contrast CT, 91% (30/33) were hypoattenuating. Central stellate scar was present in 73% (24/33). In FLHCC having central stellate scar, calcification within the central scar was seen in 88% (21/24). In the hepatic arterial phase, 82% (27/33) were hyperattenuating relative to liver. In the portal venous phase, 36% (12/33) were hyperattenuating, 46% (15/33) were isoattenuating, and 18% (6/33) were hypoattenuating. In the delayed phase images, 24% (8/23) were hyperattenuating, 67% (22/33) were isoattenuating, and 9% (3/33) were hypoattenuating. Delayed enhancement of the central stellate scar was seen in 12% (4/33). Distant metastases were seen in 54% (18/33). The most common site of metastases was lungs and was seen in 89% (16/18) of the patients with metastatic disease.
CONCLUSION: FLHCC typically manifests as a large, solitary mass demonstrating heterogeneous hypervascular enhancement in the arterial phase. Most tend to be isoattenuating in delayed phase. Central stellate scar with internal calcification is a useful imaging feature that can help in the diagnosis of FLHCC. Lungs are the most common site of distant metastases in FLHCC.