Incidental Finding of Moderna COVID-19 Vaccination-Related Axillary Lymphadenopathy on 201Tl Myocardial Perfusion Imaging.

ABSTRACT: We presented here a 71-year-old man with a history of thyroid cancer post total thyroidectomy and 131I ablation and right renal cell carcinoma post right partial nephrectomy. He reported persistent chest tightness and pain after the first dose of the Moderna COVID-19 (mRNA-1273) vaccine. Thus, coronary heart disease was suspected, and the patient was referred for MPI (myocardial perfusion imaging). Focal 201Tl uptake in the left axillary region was found incidentally on MPI, and SPECT/CT revealed enlarged benign-looking lymph nodes. The diagnostic is in favor of reactive hyperplasia after the intramuscular injection of vaccine into left deltoid muscle.

A 71-year-old man with known thyroid cancer status post total thyroidectomy and 131I ablation in 2012 and right renal cell carcinoma status post right partial nephrectomy in January 2018 under posttreatment follow-up was presented. He also has hypertension and hyperlipidemia on treatment. He felt persistent chest tightness and chest pain after the first dose of the Moderna COVID-19 (mRNA-1273) vaccine. He was referred for a myocardial perfusion imaging (MPI) examination due to suspicious coronary heart disease. MPI results showed unlikely myocardial ischemia. However, 201Tl-avid focal uptake was found incidentally over the left axillary region on MPI SPECT (A, black arrowhead) and MIP images (B, black arrow). Because of his previous cancer history, SPECT/CT was arranged, which revealed a cluster of lymph nodes in the left axilla (C, transaxial slice, white arrowhead; D, transaxial slice, white arrows), the largest one is 1.5 cm in diameter. Because the patient received a Moderna COVID-19 vaccine in the left upper arm 6 days ago, reactive axillary nodes ipsilateral to the intramuscular injection site are more favored than lymph node metastasis. COVID-19, caused by SARS-CoV-2 infection, is a global pandemic. The course of the disease could range from asymptomatic to death. Moderna, using mRNA biotechnology, is one of COVID-19 vaccines with Emergency Use Authorization. According to SNMMI statement, reactive lymphadenopathy has been reported approximately 16% of the patients who received COVID-19 mRNA vaccines.[1] Previous reports have showed that axillary lymphadenopathy was found on FDG PET/CT after various vaccines injection.[2-5] Lymph nodes are mostly affected in an intramuscular site of ipsilateral deltoid vaccination seen on FDG PET/CT; however, contralateral lymph nodes may also show FDG uptake.[6] Instead of FDG and 201Tl, COVID-19 vaccines can lead mild accumulation of some other tracers that was issued in published articles.[7-9] Nevertheless, it is sometimes limited and confused for evaluating between malignancy and inflammatory disease in breast cancer, lymphoma, or melanoma.[10] By this case, we report a very rare imaging on 201Tl MPI of incidental finding axillary lymphadenopathy after 6 days of COVID-19 vaccination. With the increasing rate of COVID-19 vaccination in present day,[11] a careful review of the clinical record and raw data of imaging is necessary for interpretation of axillary lymphadenopathy, especially in patients with cancer history.