Abstract

Introduction: The coronavirus disease 2019 (COVID-19) caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), has caused effects on cancer patients including cancer screening process, risk factor records, cancer diagnoses, cancer treatment and follow-up. Nowadays, the COVID-19 vaccine has been used around the world and it has resulted axillary lymphadenopathy reaction. Unilateral axial lymphadenopathy which located near the vaccine injection site following COVID-19 vaccination is common of expecting adverse reaction especially happened in mRNA vaccine (Pfizer-BioTech and Moderna). In this COVID-19 pandemic, physicians should be aware of this follow-up process to avoid false positive cancer diagnosis and inform patient of unnecessary investigation, or delayed cancer diagnosis because suspected COVID-19 vaccination reaction instead of cancer diagnosis. Case report: We present two cases of a 47-year-old female and 34-year-old with no medical history, admitted to Department of Breast and Gynecologic cancer, Danang Oncology Hospital because of axillary lymphadenopathy that occurred after COVID-19 vaccination. Conclusion: After reviewing the literature, ipsilateral injection side axillary lymphadenopathy has been reported. Therefore, physician as well as oncologist working in the era of COVID-19 should be obtained information regarding COVID-19 vaccination including injected time, injected arm, and the symptoms after vaccinating to ensure the accuracy diagnosis and to avoid unnecessary biopsy and the possibility of a misdiagnosis. We recommend to perform cancer screening before vaccination or consider delay breast cancer screening exams until 4-6 weeks after vaccination, and the patient can undergo short term follow-up in the three months to ensure resolution.