Negative 68Ga-FAPI-04 Uptake on PET/CT in HNF-1α–mutated Hepatocellular Adenoma

A 37-year-old woman was incidentally found to have a hepatic lesion on ultrasound. Serum tumor markers, including AFP, CEA, and CA19-9, were normal. Gd-EOB-DTPA-enhanced MRI revealed a fat-containing lesion with arterial phase hyperenhancement, rapid washout, hypointensity in the hepatobiliary phase, and no diffusion restriction, making it difficult to differentiate between hepatic adenoma (HCA) and small hepatocellular carcinoma (HCC). 18F-FDG PET/CT revealed intense uptake, raising suspicion of malignancy, while 68Ga-FAPI-04 PET/CT demonstrated negligible uptake. Histopathology confirmed hepatocyte nuclear factor 1α (HNF1α)-mutated hepatocellular adenoma (H-HCA). This case may provide valuable insights into differentiating H-HCA from small HCC.