Characteristics of atypical large well-differentiated hepatocellular carcinoma: a specific subtype of hepatocellular carcinoma?

Abstract Background Hepatocellular carcinoma (HCC) de-differentiation is thought to correlate with size, therefore well-differentiated HCC ≥3 cm are considered rare and not fully understood. Methods Patients who underwent hepatectomy for HCC between 1998–2016 were retrospectively analyzed. Patient's characteristics and recurrence-free (RFS) and overall (OS) survival were compared between those with atypical- (well-differentiated-HCC ≥3 cm) and typical-HCC (moderate-to-poorly-differentiated HCC ≥3 cm). Results Of 176 patients included in this study, 37 (21%) had atypical-HCC. Patients with atypical-HCC were less likely to be Asian ethnicity (3% vs. 17%, p = 0.062), have lower rate of viral infection (14% vs. 43%, p = 0.003), cirrhosis (8% vs. 27%, p = 0.015). The tumors were less likely to demonstrate vascular invasion (30% vs. 59%, p = 0.002), and were associated with a lower alpha-fetoprotein level (3.5 ng/ml vs. 33.2 ng/ml, p  Conclusion Patients with atypical-HCC have different characteristic in terms of epidemiology, etiology, cirrhosis and vascular invasion as compared to typical-HCC. The etiology of atypical-HCC may be non-alcoholic fatty liver disease-related and/or malignant transformation of hepatocellular adenoma.