Mild-to-moderate irregular increased 18F-FDG uptake along a neurovascular bundle was observed (figure, video). Since the initial clinical manifestation in patient 1 was not typical of Guillain-Barré syndrome, high-dose methylprednisolone therapy was initiated under the suspicion of inflammatory peripheral polyneuropathy or a lymphoma relapse. Patient 1 fulfilled level 2 of the Brighton criteria for diagnostic certainty and patient 2 fulfilled level 1 of these criteria.6 The calculated Naranjo adverse reaction scale score was 7, suggesting a probable association between the vaccination and Guillain-Barré syndrome.7 However, we cannot confirm the causal relation between Guillain-Barré syndrome and the BNT162b2 COVID-19 vaccine, since the two cases of Guillain-Barré syndrome reported could be coincidental, and our report presents the temporal relation (within 4 weeks) only. ...an extensive vaccination drive that is underway, including all age groups (from young people to older adults), is an unprecedented event in the COVID-19 era. ...we might now observe the development of Guillain-Barré syndrome among patients with diffuse large B-cell lymphoma.