Hepatocellular adenoma displaying a HNF1α inactivation in a patient with familial adenomatous polyposis coli

Patients with familial adenomatous polyposis coli (FAP) may rarely develop hepatocellular adenoma. Here we report the case of a 37-year-old FAP woman presenting a hepatocellular adenoma after oestroprogestative oral contraception use. In this steatotic adenoma, we identified an inactivating biallelic mutation of HNF1α. In addition to the known germline APC mutation Q1062fs, we did not find an inactivation of the second APC allele nor an activation of the β-catenin target genes GLUL and GPR49. Our findings contrast with two hepatocellular adenoma cases related to FAP, for which a biallelic inactivation of the APC gene was previously described. Altogether, these results suggest that benign hepatocellular carcinogenesis may be dependent on or independent of the Wnt/β-catenin pathway in patients with FAP.