Macrotrabecular‐massive hepatocellular carcinoma: A distinctive histological subtype with clinical relevance

We recently identified a novel histological subtype of hepatocellular carcinoma, designated as "macrotrabecular-massive" (MTM-HCC) and associated with specific molecular features. In order to assess the clinical relevance of this novel variant, we aimed to investigate its prognostic value in two large series of patients with HCC treated either by surgical resection or radiofrequency ablation (RFA). We retrospectively included 237 HCC surgical samples and 284 HCC liver biopsies from patients treated by surgical resection and RFA, respectively. Histological slides were reviewed by pathologists specialized in liver disease, and the MTM-HCC subtype was defined by the presence of a predominant (>50%) macrotrabecular architecture (more than 6 cells thick). The main clinical and biological features were recorded at baseline. Clinical endpoints were early and overall recurrence. The MTM-HCC subtype was identified in 12% of the whole cohort (16% of surgically resected samples, 8.5% of liver biopsy samples). It was associated at baseline with known poor prognostic factors (tumor size, AFP level, satellite nodules and vascular invasion). Multivariate analysis showed that MTM-HCC subtype was an independent predictor of early and overall recurrence (surgical series: OR 3.03 (1.38-6.65), p=0.006 and 2.76 (1.63-4.67), p<0.001); RFA series: 2.37 (1.36-4.13), p=0.002 and 2.19 (1.35-3.54), p=0.001, respectively). Its prognostic value was retained even after patients stratification according to common clinical, biological and pathological features of aggressiveness. No other baseline parameter was independently associated to recurrence in the RFA series.