Pulmonary Adenocarcinoma Metastasis to the Breast Unexpectedly Discovered on Re-staging ¹⁸F-FDG PET/CT in a Woman With a Normal Screening Mammogram

Fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography is a commonly performed, highly sensitive tool to stage and restage many lung cancers. Unexpected fluorine-18 fluorodeoxyglucose uptake in patients with known cancers is common and can require additional diagnostic workup. Although lung and breast cancers are common and the 2 leading causes of cancer deaths in women, lung adenocarcinoma metastatic to the breast has rarely been described in the literature.