MR Imaging of Hepatocellular Adenomas and Differential Diagnosis Dilemma

Abstract

Hepatocellular adenomas (HCAs) are currently categorized into distinct genetic and pathologic subtypes as follows: inflammatory hepatocellular adenoma, hepatocyte-nuclear-factor-1-alpha (HNF-1α-mutated) hepatocellular adenoma, and β-catenin-mutated hepatocellular adenomas; the fourth, defined as unclassified subtype, encompasses HCAs without any genetic abnormalities. This classification has accepted management implications due to different risks of haemorrhage and malignant transformation of the four subtypes. Imaging guided biopsy and/or surgical resection very important in obtaining definitive characterization; nevertheless, MRI with intra-extravascular and hepatobiliary (dual phase) agents, is an important tool not only in differential subtypes definition but even in surveillance with early identification of complications and discovery of some signs of HCA malignant degeneration. Inflammation, abnormal rich vascularisation, peliotic areas, and abundant fatty infiltration are pathologic findings differently present in the HCA subtypes and they may be detected by multiparametric MRI approach. Lesion enlargement and heterogeneity of signal intensity and of contrast enhancement are signs to be considered in malignant transformation. The purpose of this paper is to present the state of the art of MRI in the diagnosis of HCA and subtype characterization, with particular regard to morphologic and functional information available with dual phase contrast agents, and to discuss differential diagnosis with the most common benign and malignant lesions mimicking HCAs.

Morphologic and Molecular Features of Hepatocellular Adenoma with Gadoxetic Acid–enhanced MR Imaging

“…H epatocellular adenoma (HCA) poses a diagnostic challenge because its imaging appearance and enhancement patterns at cross-sectional imaging, including computed tomographic (CT) and magnetic resonance (MR) imaging, are variable (1)(2)(3)(4). The histopathologic work-up may be an equal challenge (5,6).…”

“…Furthermore, contrast agent retention or washout in the PV, delayed phases, and HBP was documented. Finally, from the MR imaging findings evaluated, each radiologist was asked to make an a priori diagnosis for each lesion detected on the basis of typical features of those lesions, as previously published (2,4,11,(13)(14)(15)(16)(17)25). …”

Hepatic Lymphoma Representing Iso-Signal Intensity on Hepatobiliary Phase, in Gd-EOB-DTPA-Enhanced MRI: Case Report

“…In MRI, most cases show low signal or iso-signal intensity on T1 weighted imaging, and moderate high signal intensity on T2 weighted imaging. Typically, lymphoma shows low signal intensity on arterial phase after contrast enhancement and homogeneous delayed enhancement in the portal venous phase, with isosignal intensity in the transitional phase (1,(3)(4)(5). Low signal intensity has been shown in the hepatobiliary phase using a hepatocyte-specific contrast agent, which has recently shown increasing access (3,4).…”

“…The image findings of hepatic lymphoma have been reported as variable, ranging from single or multiple nodules to diffuse infiltrates (1,2). It is known that hepatic lymphomas show low signal intensity on T1 weighted images, high signal intensity on T2 weighted images, and low signal intensity on hepatobiliary phase image, using hepatocyte-specific contrast agents (3,4). Here, we report an atypical case of hepatic lymphoma showing iso-signal intensity on hepatobiliary phase of contrast-enhanced MRI using gadoxetic acid (Gd-EOB-DTPA, Primovist; Bayer Schering Pharma, Berlin, Germany).…”

Primary Hepatic Mucosa-Associated Lymphoid Tissue Lymphoma: A Case Report

“…Primary hepatic MALT lymphoma is an extremely rare lesion, with only 45 cases reported in the English literature (4,5). Because of its rarity, the radiologic findings in patients with this lesion are seldom described, to our best knowledge.…”