# COVID-19 vaccination may cause FDG uptake beyond axillary area

Vincent Fleury, Bruno Maucherat, Daniela Rusu, Frédéric Dumont, Caroline Rousseau

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Vincent Fleury, Bruno Maucherat, Daniela Rusu, Frédéric Dumont, Caroline Rousseau. COVID-19 vaccination may cause FDG uptake beyond axillary area. European Journal of Hybrid Imaging, 2021, 5 (1), pp.11. 10.1186/s41824-021-00105-2. hal-04937646

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Submitted on 10 Feb 2025

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Distributed under a Creative Commons Attribution 4.0 International License
# COVID-19 vaccination may cause FDG uptake beyond axillary area

Vincent Fleury<fnref n="1" />*, Bruno Maucherat<fnref n="1" />, Daniela Rusu<fnref n="1" />, Frédéric Dumont² and Caroline Rousseau<fnref n="1" />,³,⁴

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## Abstract

**Background:** The vaccination immune response may induce false-positive ¹⁸F-FDG PET/CT uptake.

**Case presentation:** An extended supraclavicular lymph nodal activation after coronavirus disease 2019 (COVID-19) vaccination revealed on ¹⁸F-FDG PET/CT mimics a Virchow nodule in a patient with medical history of well-differentiated appendicular adenocarcinoma.

**Conclusion:** This case highlights a nodal activation beyond axillary area and the importance of documenting vaccination history at the time of scanning to avoid false-positive results.

**Keywords:** FDG PET/CT, COVID-19, Vaccine

## Background

Development of vaccines to prevent COVID-19 is a hope to prevent transmission or reduce the severity of infection. However, vaccination could be a potential source of false-positive results in ¹⁸F-FDG PET/CT (Katal et al. 2021).

## Case presentation

We present the case of a 64-year-old female with well-differentiated appendicular adenocarcinoma associated with peritoneal carcinosis initially treated by surgery and chemotherapy benefited from a ¹⁸F-FDG PET/CT to investigate a peritoneal nodule (Fig. 1). This peritoneal nodule (arrow) visualized on the axial (a) view of CT image showed no increased FDG uptake on the axial (b) PET/CT fused image. The MIP (c) and axial (D) PET/CT fused images detected an intense hypermetabolism on the left axillary lymph nodes up to the left supraclavicular area. The patient revealed she had received the first of dose Pfizer BNT162b2mRNA vaccine against COVID-19 on the left shoulder intramuscular 4 days before FDG examination. In order to exclude a Virchow nodule due to her digestive cancer history, we performed a cervical echography with supraclavicular node cytological biopsy sample. Echography (E) showed a 14-mm-long axis normal lymph node with its central hilum. Cytological analysis revealed activated lymphoid cells without tumor cells.

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<footnote>* Correspondence: vfleury245@gmail.com</footnote>

<footnote n="1">¹Department of Nuclear Medicine, ICO Gauducheau Cancer Center, Boulevard Monod, 44805 Saint-Herblain Cedex, France Full list of author information is available at the end of the article</footnote>
<figure><img src="image_4.png" /><figcaption>**Fig. 1** CT scan showed a peritoneal nodule (arrow in a) with no increased uptake on fused ¹⁸F-FDG PET/CT images (arrow in b). MIP (c) and fused ¹⁸F-FDG PET/CT (d) showed with increased uptake on the left axillary lymph nodes up to the left supraclavicular area. Echography (e) showed a normal supraclavicular lymph node</figcaption></figure>

**Discussion**

Several previous reports have demonstrated axillary lymph nodal activation on ¹⁸F-FDG PET/CT following influenza and COVID-19 vaccination (Burger et al. 2011; Shirone et al. 2012; Eifer et al. 2021; Nawwar et al. 2021). This case revealed an atypical extended supraclavicular activation. In the context of the COVID-19 pandemic and large vaccination programs, questionnaires including date and location of the vaccination can help to avoid false-positive lymph node interpretation with the risk of a therapeutic choice impact offered to the patient. In patients with solid tumor like breast cancer or melanoma, the vaccination should be performed in the contralateral arm to limit misinterpretations. Otherwise, it would be advisable to respect a time interval to define between the vaccination and ¹⁸F-FDG PET/CT scan.

**Conclusion**

Nuclear physicians should be careful when cancers staging and re-staging. This is especially important for patients with breast cancer having been vaccinated on the homolateral upper limb, digestive cancer patients vaccinated on the left side, or with lung or head and neck carcinoma.

**Acknowledgements**

Not applicable

**Authors' contributions**

Conception and design: VF; BM; DR; FD; CR. Acquisition of data, analysis and interpretation of data: VF; BM; DR; FD; CR. Drafting the article and final approval of the revised manuscript: VF; BM; DR; FD; CR. All authors read and approved the final manuscript.

**Funding**

No funding

**Availability of data and materials**

Not applicable

**Declarations**

**Ethics approval and consent to participate**

As the FDG-PET/CT was part of a routinely performed clinical examination, no ethics approval was needed.
**Consent for publication**

For this case report, the patient has consented to the submission.

**Competing interests**

The authors declare that they have no conflicts of interest or competing interests.

**Author details**

¹Department of Nuclear Medicine, ICO Gauduchau Cancer Center, Boulevard Monod, 44805 Saint-Herblain Cedex,, France. ²Department of Surgical Oncology, ICO Gauduchau Cancer Center, Saint-Herblain, France. ³CNRS, Inserm, CRCI NA, Nantes, France. ⁴Nantes University, Nantes, France.

Received: 11 April 2021 Accepted: 10 May 2021

Published online: 01 June 2021

**References**

Burger IA, Husmann L, Hany TF, Schmid DT, Schaefer NG (2011) Incidence and intensity of F-18 FDG uptake after vaccination with H1N1 vaccine. Clin Nucl Med. 36(10):848–853. https://doi.org/10.1097/RLU.0b013e3182177322

Eifer M, Eshet Y (2021) Imaging of COVID-19 vaccination at FDG PET/CT. Radiology. 28:210030

Katal S, Pouraryan A, Gholamrezanezhad A (2021) COVID-19 vaccine is here: practical considerations for clinical imaging applications. Clin Imaging. 76:38–41. https://doi.org/10.1016/j.clinimag.2021.01.023

Nawwar AA, Searle J, Hagan I, Lyburn ID (2021) COVID-19 vaccination induced axillary nodal uptake on [18F]FDG PET/CT. Eur J Nucl Med Mol Imaging. 26:1–2

Shirone N, Shinkai T, Yamane T, Uto F, Yoshimura H, Tamai H, Imai T, Inoue M, Kitano S, Kichikawa K, Hasegawa M (2012 Apr) Axillary lymph node accumulation on FDG-PET/CT after influenza vaccination. Ann Nucl Med. 26(3):248–252. https://doi.org/10.1007/s12149-011-0568-x

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