COVID-19 Post-Vaccinal Lymphadenopathy Mimicking Lymph Node Metastases from Breast Neoplasia

Since the effective start of the large vaccination campaigns against the Coronavirus disease 19 (COVID-19) pandemic, case reports are rising concerning unilateral axillary lymphadenopathies highly uptaking FDG PET/CT scans. These lymphadenopathies can be a source of false positive for FDG PET/CT in a post-vaccination context. We report here the case of a 59-year-old womanfor whom a FDG PET/CT has been performed as part of the initial extension assessment of a recurrence of a left breast, 15 days after receiving her first dose of Moderna COVID 19 vaccine. Apart from the primary mammary lesion, the FDG PET CT revealed multiple unilateral axillary lymphadenopathies whose neoplastic nature was excluded after an accurate interview and confirmed after a histological examination. This case confirms the key role of a detailed interview before performing an FDG PET/CT examination to reduce false positives as much as possible.