The Day after Mass COVID-19 Vaccination: Higher Hypermetabolic Lymphadenopathy Detection on PET/CT and Impact on Oncologic Patients Management

• Main Authors: Cristina Ferrari, Anna Giulia Nappi, Giulia Santo, Paolo Mammucci, Dino Rubini, Marco Tucci, Antonio Rosario Pisani
• Format: Article
• Language: English
• Published: MDPI AG 2021-08-01
• Series: Cancers
• Subjects: COVID-19; positron emission tomography; PET/CT; vaccination; axillary lymph nodes; oncologic imaging
• Online Access: https://www.mdpi.com/2072-6694/13/17/4340

The widespread COVID-19 vaccination led to unexpected PET findings. Notably, axillary and interpectoral lymphadenopathies ipsilateral to the vaccine inoculation were observed. We aimed to assess the hypermetabolic lymphadenopathy (HLN) detection rate on PET/CT. Secondly, we investigated factors that might help in HLN differential diagnosis. A retrospective analysis on 1196 consecutive patients referred for a PET/CT was performed. All patients were asked about the date, type and site of vaccine injections. HLNs were recorded and categorized according to risk classes and SUVmax grades. A statistical analysis was performed to assess the correlation between HLN detection and different clinical/vaccine data. HLN detection rate was 15% and 27% in the No Vac- and vac-groups (<i>p</i> < 0.001), respectively. In the Vac-group, age (<i>p</i> < 0.001) and time interval from vaccine-to-PET (<i>p</i> = 0.010) were inversely correlated with HLN detection. Furthermore, SUVmax significantly changed during time intervals, with lower values beyond 20 days (<i>p</i> < 0.001). In the era of mass COVID-19 vaccination, a higher axillary and interpectoral lymphadenopathies detection ipsilateral to vaccine injection was observed. These PET findings can be wrongly interpreted, complicating cancer patients’ management. To minimize these pitfalls, a detailed vaccination anamnesis must be recorded and should take into account the appropriate PET schedule.