Uncommon liver tumors

BACKGROUND Beside hepatocellular carcinoma, metastasis, and cholangiocarcinoma, the imaging findings of other relatively uncommon hepatic lesions are less discussed in the literature. Imaging diagnosis of these lesions is a daily challenge. In this article, we review the imaging characteristics of these neoplasms. METHODS From January 2003 to December 2014, 4746 patients underwent liver biopsy or hepatic surgical resection in our hospital. We reviewed the pathological database retrospectively. Imaging of these lesions was reviewed. RESULTS Imaging findings of uncommon hepatic lesions vary. We discuss the typical imaging characteristics with literature review. Clinical and pathological correlations are also described. Primary hepatic lymphoma consists only of 1% of the extranodal non-Hodgkin lymphoma, and is defined as the one involving only the liver and perihepatic lymph nodes within 6 months after diagnosis. Combined hepatocellular and cholangiocarcinoma (cHCC-CC) shares some overlapping imaging characteristics with both HCC and cholangiocarcinoma because of being an admixture of them. Angiosarcoma is the most common hepatic mesenchymal tumor and is hypervascular in nature. Inflammatory pseudotumor is often heterogeneous on ultrasonography and with enhanced septations and rims in the portovenous phase after contrast medium. Angiomyolipoma (AML) typically presents with macroscopic fat components with low signal on fat-saturated magnetic resonance imaging (MRI) and presence of drainage vessels. Intraductal papillary neoplasm of the bile duct (IPNB) is thought of as a counterpart to the pancreatic intraductal papillary mucinous neoplasm. Most of the IPNBs secrete mucin and cause disproportional dilatation of the bile ducts. Mucinous cystic neoplasm (MCN) contains proteinaceous and colloidal components without ductal communication and characterizes with hyperintensity on T1-weighted imaging. Other extremely rare lesions, including epithelioid hemangioendothelioma and inflammatory pseudotumor-like follicular dendritic cell sarcoma, are also discussed. Hepatoblastoma and mesenchymal hamartoma, mostly in children, are also briefly reviewed as well. CONCLUSION It is important for radiologists to be familiar with the typical imaging features of the uncommon hepatic neoplasms. If imaging findings are not typical or diagnostic, further biopsy is required.