CTNNB1 mutations in serum amyloid A-positive hepatocellular neoplasm/inflammatory hepatocellular adenoma arising in alcoholic cirrhosis

Background

Serum amyloid A-positive hepatocellular neoplasm (SAA-HN) arising in alcoholic cirrhosis is now regarded as a specific type of inflammatory hepatocellular adenoma (IHCA) associated with advanced liver disease. Since recent studies reported various glutamine synthetase (GS) expression patterns corresponding to CTNNB1 mutations in β-catenin mutated HCA, SAA-HN/IHCAs were herein re-evaluated for CTNNB1 mutations.

Methods

GS expression was examined in 33 SAA-HN/IHCAs (23 patients) and 15 IHCAs (14 patients) from our archives and classified into patterns (P) 1–3 (P1, a diffuse homogeneous pattern suggesting an exon 3-non-S45 mutation; P2, diffuse heterogeneous, suggesting an exon 3-S45 mutation; P3, rim and focal heterogeneous, suggesting exon-7/8 mutations) and P4 (negative). Hotspot genetic mutations in CTNNB1, exons-3, 7, and 8 were examined by direct sequencing.

Results

Thirty-three SAA-HN/IHCAs were classified into 3 P1, one P3, and 29 P4 and 15 HCAs into 3 P1, 1 P2, 2 P3, and 9 P4. A genetic analysis revealed 3 SAA-HN/IHCAs with CTNNB1, exon-3 mutations and 1 exon-7 mutation, consistent with GS expression patterns P1 and P3, respectively. Two SAA-HN/IHCAs were associated with CTNNB1, exon-8 mutation, and both were regarded as P4 based on GS expression patterns. No significant differences were observed in clinicopathological features between SAA-HN/IHCAs with and without CTNNB1 mutations (p > 0.05).

Conclusions

Some SAA-HN/IHCAs may be b-IHCA, exon-3 or exon-7/8 mutations. Careful evaluation of immunoreactivity for GS and a genetic analysis of CTNNB1 mutations are crucial for the accurate diagnosis of b-IHCA, exon-3 mutation, for which the risk of malignant transformation is high, and better clinical management.