A Case of Intense 18 F-fluoroestradiol ( 18 F-FES) Uptake in Hepatic Focal Nodular Hyperplasia.

Kitano, Yurika; Miyake, Kanae K; Kawashima, Masahiro; Shimizu, Yoichi; Nakamoto, Yuji · Clin Nucl Med · 2026

case_report · Level V

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Abstract

We report the first documented case of focal nodular hyperplasia (FNH) demonstrating intense uptake on 18 F-fluoroestradiol ( 18 F-FES) PET/CT. A 46-year-old premenopausal woman with newly diagnosed ER-positive invasive lobular breast cancer underwent whole-body 18 F-FES PET/CT, which incidentally revealed a 3-cm hepatic mass with uptake comparable to physiological liver activity. Multimodality imaging (MRI, dynamic CT, and Sonazoid ultrasonography) showed characteristic features of FNH, which remained stable for 4 years. This case demonstrates that FNH can exhibit marked FES uptake. Awareness of this benign cause of FES avidity is important to avoid misinterpreting hepatic FES-avid lesions as metastasis.

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