Upstaging of Invasive Lobular Cancer With FES PET/CT.

A 78-year-old woman diagnosed with left breast invasive lobular carcinoma with left axillary nodal metastasis underwent 18 F-fluoroestradiol (FES) PET/CT imaging for further evaluation of indeterminate right axillary lymph nodes seen on staging 18 F-FDG PET/CT. 18 F-FES PET/CT revealed abnormal 18 F-FES-avid right axillary and bilateral cervical nodes, subsequently biopsy-proven metastases, upstaging the patient from stage II to IV and greatly changing patient management. This case demonstrates the value of 18 F-FES PET/CT in accurately staging metastatic invasive lobular carcinoma at diagnosis, an indication for which 18 F-FES PET/CT "may be appropriate" per current Society of Nuclear Medicine and Molecular Imaging guidelines.