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

Abstract

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 (p < 0.001), respectively. In the Vac-group, age (p < 0.001) and time interval from vaccine-to-PET (p = 0.010) were inversely correlated with HLN detection. Furthermore, SUVmax significantly changed during time intervals, with lower values beyond 20 days (p < 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.

COVID-19 vaccination, implications for PET/CT image interpretation and future perspectives

“…Ferrari et al [ 13 ] assessed vaccine-related lymph nodes in a large cohort of Italian patients imaged using different tracers including [ 18 F]Fluciclovine, [ 18 F]Fluorocholine, and [ 18 F]FDG. Lymph nodes visually defined as positive were graded according to a 3-point scale based on SUVmax values (SUVmax < 2.2, 2.2 ≤ SUVmax ≤ 4, and SUVmax > 4).…”

“…Although the majority of studies included in the present review focused on [ 18 F]FDG, local signs of inflammation have been also described with other tracers [ 2 , 4 , 12 , 13 ]. Further ipsilateral supraclavicular and/or cervical “hot” lymph nodes have been reported [ 2 , 12 ].…”

“…The percentage of positivity was higher after the second dose with regard to both deltoid muscle and lymph-nodal uptake. The incidence of hypermetabolic lymph nodes appeared to be higher in the first few weeks after the injection and seems to decrease over time [ 2 , 5 , 6 , 10 , 13 – 15 ], although they may be visible even after 10 weeks [ 3 , 6 ]. Vaccine-related axillar uptake following the third vaccination usually persists just for few days (up to 5 days), rarely interfering with images’ interpretation [ 17 ].…”

Misdiagnosis of Reactive Lymphadenopathy Remotely After COVID-19 Vaccination: A Case Report and Literature Review

“…In CDC reports, lymphadenopathy occurred within 2 to 4 days after vaccination with Moderna and lasted for 1 to 2 days (11), and the duration in radiologic observational reports was longer (between 4 days and 10 weeks) (12)(13)(14)(15)(16)(17)(18). However, most of these cases were retrospective studies in the patients who recently received the COVID-19 vaccine and underwent positron emission tomography (PET).…”

Temporary reactive response of axillary lymph nodes to COVID-19 vaccination on 18F-rhPSMA-7.3 PET/CT in patients with prostate cancer

“…In times of global pandemic of Coronavirus disease 2019 (COVID-19) infections and rapidly increasing vaccinated population, Vaccine-Associated Lymphadenopathy (VAL) in axillary or supraclavicular lymph nodes ipsilateral to the vaccination site on 18 F-FDG examinations was increasingly observed (1)(2)(3)(4)(5)(6). Ipsilateral axillary lymphadenopathy following intramuscular vaccine has been observed with seasonal and H1N1 influenza and human papilloma virus vaccines (7)(8)(9)(10).…”