Ultra-Sensitive Detection of Bone Metastasis From Accessory Breast Cancer Using HER2 PET/CT: A Case Report

We presented the imaging findings of 18 F-FDG and 68 Ga-HER2 affibody PET/CT in a 52-year-old woman with HER2-positive accessory breast cancer in the right axilla. 18 F-FDG and HER2 PET/CT showed avid uptake of multiple axillary lesions. HER2 PET/CT identified extensive bone metastases with intense uptake, while the ⁹⁹ᵐTc-MDP whole bone scan was negative, and only a few bone lesions with mild tracer uptake were detected by 18 F-FDG PET/CT. Following 6 cycles of the TCbHP regimen, the axillary lesions markedly reduced. This case demonstrates that HER2 PET/CT enables more sensitive detection of HER2-positive lesions, thereby allowing for precise staging and guiding HER2-targeted therapy.