Bilateral Axillary Nodal Uptake on 99m Tc-White Blood Cell Study Secondary to COVID-19 mRNA Vaccination.

A 77-year-old man with a history of chronic lower back pain, and prior spinal fusion surgery X2 was referred for 99m Tc-WBC Study for evaluation of worsening back pain and cervical radiculopathy to rule out any signs of infection. The patients white blood cells were tagged with 99m Tc-HMPAO (hexamethylpropylene amine oxime), and planar and SPECT/CT imaging was performed at 4 and 24 hours. 99m Tc-WBC Study showed no abnormal isotope localization in the spine; however, there was an incidental finding of bilateral increased soft tissue uptake in axillary lymph nodes. Medical history revealed intramuscular injection of second and third dose of Moderna mRNA COVID-19 vaccine in bilateral deltoids approximately 11 and 5 months before scan.