[18F]-FDG PET/CT of the Pulmonary Benign Metastasizing Leiomyoma in a Breast Cancer Patient: A Case Report

18F-fluorodeoxyglucose ([18F]-FDG) positron emission tomography/computed tomography (PET/CT) is a useful functional image technique to evaluate the disease extent in many cancers, as well as differentiate benign disease from malignant metastasis. We report the case of a 49-year-old woman with breast cancer and suspected lung metastasis by conventional images. After FDG-PET/CT demonstrating faint, or even no FDG uptake in bilateral pulmonary nodules, accompanied with obvious uterine fibroids, benign metastasizing leiomyoma (BML) of the lung was included in a differential diagnosis and finally confirmed by surgical pathology. FDG PET/CT showed its value in the diagnosis of BML in the breast cancer patient who was misleading as lung metastasis during outpatient follow-up.