Comparison of computed tomography and magnetic resonance imaging findings and histopathological features of macrotrabecular-massive hepatocellular carcinoma.

Background: Macrotrabecular-massive hepatocellular carcinoma (MTM-HCC) is a novel subtype of HCC, one of eight distinct subtypes, that accounts for 5% of all cases of HCC and is associated with a worse prognosis. Preoperative diagnosis of MTM-HCCs using imaging findings can facilitate patient treatment decision-making. The purpose of this study was to describe computed tomography (CT) and magnetic resonance imaging (MRI) findings of MTM-HCCs and compare these findings with histopathological features.

Methods: This retrospective case-control study was performed at Shenzhen People's Hospital. The cohort included 17 patients with surgically confirmed MTM-HCCs and 232 patients with surgically confirmed non-MTM-HCCs who were enrolled by searching the pathological database from January 2018 to June 2022. CT and MRI findings were retrospectively analyzed and compared with pathological features. Student's -test or Mann-Whitney U test for continuous variables and χ test or Fisher's exact test for categorical variables were implemented to compare imaging manifestations between MTM-HCCs and non-MTM-HCCs, as appropriate.

Results: Seventeen tumors with a mean diameter of 8.58±2.83 cm were identified in the 17 patients. In addition to the typical findings of hepatocellular carcinomas (HCCs), such as arterial phase hyperenhancement (APHE), wash out, restricted diffusion, capsule and non-uptake at the hepatobiliary phase (HBP), the most common findings in MTM-HCCs were necrosis in 11 patients (64.7%, 11/17), followed by intratumoral arteries in 6 patients (35.3%, 6/17), peritumoral arterial transitive enhancement in 3 patients (17.6%, 3/17) and peritumoral hypointensive areas at the HBP in 3 of 8 patients (37.5%, 3/8) who received gadolinium-ethoxybenzyl-diethylenetriamine penta-acetic acid (Gd-EOB-DTPA) enhancement. The tumor size of non-MTM-HCCs was 5.26±1.94 cm, which was smaller than the 8.58±2.83 cm of MTM-HCCs (P<0.001). The frequency of necrosis and intratumoral arteries was significantly higher in MTM-HCCs than in non-MTM-HCCs (necrosis: 64.7% 34.6%, P=0.012; intratumoral arteries: 47.1% 19.7%, P=0.008).

Conclusions: MTM-HCCs tend to be large in size with intratumoral artery and intratumoral necrosis, which are characteristics that may distinguish them from non-MTM-HCCs.