Unique genetic alterations and clinicopathological features of hepatocellular adenoma in Chinese population

Hepatocellular adenoma (HCA) is a benign hepatocyte-derived tumor commonly seen in reproductive-aged women with long-term use of oral contraceptives (OCs) in European and North American countries. Accordingly, HCA is currently classified into four molecular subtypes as adopted by the World Health Organization. The present study was firstly to characterize and determine the genetic alterations and clinicopathological features of the largest series of HCAs in China. We reviewed 189 patients with HCA who underwent hepatectomies at our liver center from January 1984 to January 2012, among which 36 HCAs were randomly selected for the sequencing of HNF1α, β-catenin and gp130 genes, and 60 HCAs were randomly selected for detecting microsatellite instability (MSI). Compared with Western studies, our data showed distinctive findings including male (69.8%) and overweight/obese (50.3%) predominance. Only 3.5% of female patients had a documented history of OCs use for 2-4 years. All 36 sequenced HCAs showed HNF1α mutations (72% missense, 28% synonymous), 2 hotspot polymorphisms of HNF1α (I27L: rs1169288 and S487N: rs2464196) were seen in 17 (47%) and 10 (27.8%) cases, respectively, and a novel single nucleotide polymorphism site (rs1169304) in intron 9 of HNF1α was detected in 32 (88%) cases, but no β-catenin or gp130 gene mutation was detected, and no nuclear β-catenin staining was detected by immunohistochemistry. The frequency of MSI was 75% for D12S1398 (HNF1α inactivated pathway) and 78.5% for D6S1064 (HIPPO signaling pathway) in 34 overweight/obese patients with HCA. Our results firstly indicate that patients with HCA in China frequently occur in male overweigh and obese adult population, lack an association with OCs use and exhibit unique genetic alterations. Taken together, these observations suggest that alternative pathogenetic pathways involve in HCA tumorigenesis in Chinese patients.