Diagnosis of hepatocellular adenoma in men before onset of diabetes in HNF1A‐MODY: Watch out for winkers

Hepatocyte nuclear factor 1A (HNF1A) maturity‐onset diabetes of the young (MODY) is a monogenetic, autosomal dominantly inherited form of diabetes. HNF1A‐MODY is associated with HNF1A‐inactivated hepatocellular adenoma (H‐HCA) formation. Hepatocellular adenoma (HCA) are benign liver tumours and related complications are rare but serious: hepatic haemorrhage and malignant transformation. Guidelines recommend resection of all HCA in men and do not take any co‐occurring metabolic disorders into account. We report a family with HCA preceding diabetes mellitus. Male index patient presented with numerous, irresectable HCA. After initial diagnostic and aetiologic uncertainty HNF1A germline mutation c.815G>A (p.Arg272His) was confirmed 8 years later. No HCA‐related complications occurred. His diabetic mother was diagnosed with HCA after severe hepatic haemorrhage years before. HNF1A‐MODY should be considered in (non‐)diabetic (male) patients with H‐HCA. We advocate liver biopsy and, if necessary, genetic analysis to precede any intervention for HCA in males and screening for HCA in HNF1A‐MODY patients.