CT findings of primary clear cell carcinoma of liver: with analysis of 19 cases and review of the literature.

PURPOSE: To analyze CT characteristics of primary clear cell carcinoma of the liver (PCCCL) and improve the current understanding and diagnose accuracy of the tumor. METHODS: Pre- and post-contrast CT images of 19 patients with pathology proven PCCCL were retrospectively analyzed. The clinical data and CT findings as well as relevant literature reports were reviewed. RESULTS: Thirteen patients were tested positive for HBsAg, and two patients were positive for HCVAb. The serum alpha-fetoprotein (AFP) levels of most tumors (14/19) were ≤20 ng/ml with 14 cases were associated with liver cirrhosis. All lesions were solitary intraparenchymal mass lesions which have well-defined boarders. On pre-contrast CT scans, 15 lesions appeared as hypo-attenuation and four lesions appeared as isointensity to the adjacent liver parenchyma. On post-contrast CT scans, 16 lesions showed avid enhancement on the hepatic arterial phase, of which 6 lesions were hypo-attenuation, and 10 lesions remained slightly hyper-attenuation or iso-attenuation on the portal venous phase images. Three lesions showed only mild enhancement on the hepatic arterial phase and hypo-attenuation on the portal venous phase. All lesions demonstrated hypointensity on the equilibrium phase. There are 12 lesions showed pseudocapsules. None of patients showed signs of portal vein thrombosis. There was no distal metastasis except only one patient had lymph node metastasis. CONCLUSION: The characteristics of CT imaging of PCCCL, such as tend to form pseudocapsules and less involved with vascular invasion, could be useful in differentiating from common type hepatocellular carcinoma (CHCC). Some CT imaging characteristics of PCCCL are similar to CHCC, such as prone to occur in patients with liver cirrhosis and early enhancement pattern on the hepatic arterial phase as well as hypo-attenuation on the equilibrium phase. Those features could be useful in differentiating PCCCL from other liver tumors, such as hemangioma and hepatic metastases.