We report the case of a 67-year-old woman who had been treated for an early stage left invasive breast carcinoma with tumorectomy. Given the positive sentinel lymph node, she underwent a staging [18F]-FDG PET/CT twenty days after surgery, which showed a diffusely high spleen glucose metabolism associated with hypermetabolic right axillary lymph nodes (
Figure 1). Five days before imaging, she had been administered her first dose of the COVID-19 viral vector vaccine (AZD1222) in the right upper arm without any early side effects.
Upon questioning, the patient had no history of treatment or disease that could potentially influence metabolic activity in lymphoid tissues such as corticosteroids or G(M)-CSF [
2] received over the last six months, history of chronic inflammatory [
3], auto-immune, or hematologic [
4] or infectious disease [
5]. We thus assumed that the high glucose metabolism within the right axillary lymph nodes and spleen were presumably attributable to a regional and systemic immune response, respectively.
While hypermetabolic axillary lymph nodes have been widely described upon COVID-19 vaccination, as well as with messenger RNA [
6] or vector vaccines [
7], the increased uptake within the whole spleen seems more scarce. Steinberg et al. recently reported the case of a 65-year-old woman who had her first dose of the mRNA-1273 COVID-19 vaccine and who developed a systemic inflammatory response syndrome (SIRS) within 1 day of the injection [
8]. The symptoms finally resolved 3 days after the vaccination, and the [18F]-FDG PET/CT performed 2 days later revealed a diffusely high spleen glucose metabolism associated with hypermetabolic right axillary lymph nodes (vaccination in the right deltoid). Therefore, our clinical presentation differs in two respects: on the one hand, our patient received a viral vector vaccine, and on the other hand, she remained asymptomatic in the days following the vaccination.
Overall, this brief report suggests that nuclear physicians should be aware of the clinical and imaging patterns of the immune response to vaccination, especially in the context of the current COVID-19 pandemic.
In conclusion, these recent findings open up new prospects for the future beyond COVID-19, notably with the emergence of the cancer vaccine in immuno-oncology [
9]. Extending that thought, we might expect to visualize anti-tumor immune responses in vivo with [18F]-FDG PET/CT. Nevertheless, further studies are warranted to investigate and clarify this potential new indication for [18F]-FDG PET/CT.
Author Contributions
Conceptualization, R.-D.S. and C.P.; software, R.-D.S.; validation, R.-D.S., L.C. and C.P.; investigation, R.-D.S. and N.D.; data curation, C.P.; writing—original draft preparation, C.P.; writing—review and editing, R.-D.S.; visualization, R.-D.S. and C.R.; supervision, L.C. All authors have read and agreed to the published version of the manuscript.
Funding
This research received no external funding.
Institutional Review Board Statement
The IRB of our institution waived the need for patient consent form for this retrospective study (“rule of non-opposition”). The study was performed conducted in compliance with the Declaration of Helsinki.
Informed Consent Statement
The IRB of our institution waived the need for patient consent form for this retrospective study (“rule of non-opposition”).
Data Availability Statement
The data presented in this study are available on request from thecorresponding author.
Conflicts of Interest
The authors declare no conflict of interest.
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