Pitfalls and artifacts of FDG PET/CT in recurrent breast cancer patients

Purpose: FDG PET/CT is often indicated in breast cancer patients for the detection of recurrent disease. However, the differential diagnosis between benign and malignant lesions is sometimes difficult to address, especially in organs that are often a potential site of recurrent disease. The present collection of clinical cases aims to provide some information on these likely sites of false-positive findings at FDG PET/CT in breast cancer patients and to give some physiopathological explanations. Methods: A search of the literature was performed for articles published between 2011 and 2016 that reported data on false-positive findings in patients with suspicious breast recurrence undergoing FDG PET/CT. Moreover, all false-positive findings at FDG PET/CT from a single institutional collection between 2011 and 2016, in the same setting of patients were recovered and singularly described. Results: From a search of the literature using different keywords, 57 articles reporting false-positive findings at FDG PET in recurrent breast cancer were found. However, from a careful analysis, 10 reports were used for the analysis of data. Mediastinal and loco-regional lymph nodes represent the most common site for false-positive findings at FDG PET/CT (n = 33/74; 44.6% of subjects with available results) in breast cancer patients linked to different benign conditions. Moreover, from an institutional collection of data, 15 cases were carefully described, including explanations about their physiopathological mechanisms. Conclusions: FDG PET/CT images in recurrent breast cancer patients should be carefully read to avoid over diagnosis of metastatic disease. False-positive findings should be clearly considered, especially in regional lymph nodes. Moreover, correlative CT information and clinical history including recent treatment and procedures are key in avoid false-positive finding.