Intense 18F-FAPI Uptake in Small Recurrent Lesions of Combined Hepatocellular-Cholangiocarcinoma Negative on 18F-FDG PET/CT

A 70-year-old man presented with combined hepatocellular-cholangiocarcinoma underwent partial hepatectomy and chemoradiotherapy approximately 3 months ago. Follow-up abdominal ultrasound detected a new small lesion with decreased echogenicity in the hepatic segment I, potentially indicating recurrence. The patient was enrolled in a clinical trial of comparison of 18 F-FDG and 18 F-FAPI PET/CT in hepatic lesions. Compared with non- 18 F-FDG avidity, 18 F-FAPI PET/CT showed intense tracer uptake of the hepatic lesion. Resection of the lesion was subsequently performed, and pathologic analysis confirmed the diagnosis of recurrent combined hepatocellular-cholangiocarcinoma.