Purpose: Vaccine-associated hypermetabolic lymphadenopathy (VAHL) is frequently observed on [18F]FDG PET-CT following BNT162b2 administration. Recent data suggest a prominent B-cell germinal-center (GC) response elicited by mRNA vaccines in draining lymph nodes. Thus, in this study we aimed to explore the correlation between VAHL and humoral immunity as reflected by post-vaccination serologic testing, and by comparing the incidence of VAHL between lymphoma patients treated recently with B-cell depleting therapy and those that did not.
Methods: A total of 137 patients with hematologic malignancy that had post-vaccination [18F]FDG PET-CT were included (All-PET group), 86 received both vaccine doses before imaging (PET-2 group). Their VAHL status and grade on imaging were recorded. Among 102 lymphoma patients, 34 (33.3%) were treated during the year prior vaccination with anti-CD20 antibody containing therapy. A subgroup of 54 patients also underwent serologic testing 2-3 weeks after the booster dose, and their anti-spike titers were recorded and graded as well.
Results: The overall incidence of VAHL in patients with hematologic malignancy was 31.4%. The 34 lymphoma patients treated during the year prior vaccination with anti-CD20 antibody containing therapy had significantly lower rates of VAHL comparted to all other lymphoma patients (8.8% versus 41.2% in all-PET patients, Pv < 0.01). VAHL rates were 10% in patients with negative serology, 31.3% in patients with low anti-spike titers and 72.2% in patients with high anti-spike titers. The positive predictive values of VAHL were 90% and 93.3% in all-PET and PET-2 patients, respectively. A positive statistically significant correlation was found between VAHL and serology ranks in All-PET patients (rs = 0.530, Pv < 0.001), and stronger correlation was found in PET-2 patients (rs = 0.642, Pv < 0.001).
Conclusion: VAHL on [18F]FDG PET-CT of patients with hematologic malignancy may reflect GC B-cell proliferation and an effective humoral response elicited by BNT162b2 vaccine.

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Posted 07 Apr, 2021
On 04 Apr, 2021
Received 04 Apr, 2021
On 04 Apr, 2021
Invitations sent on 04 Apr, 2021
Posted 07 Apr, 2021
On 04 Apr, 2021
Received 04 Apr, 2021
On 04 Apr, 2021
Invitations sent on 04 Apr, 2021
Purpose: Vaccine-associated hypermetabolic lymphadenopathy (VAHL) is frequently observed on [18F]FDG PET-CT following BNT162b2 administration. Recent data suggest a prominent B-cell germinal-center (GC) response elicited by mRNA vaccines in draining lymph nodes. Thus, in this study we aimed to explore the correlation between VAHL and humoral immunity as reflected by post-vaccination serologic testing, and by comparing the incidence of VAHL between lymphoma patients treated recently with B-cell depleting therapy and those that did not.
Methods: A total of 137 patients with hematologic malignancy that had post-vaccination [18F]FDG PET-CT were included (All-PET group), 86 received both vaccine doses before imaging (PET-2 group). Their VAHL status and grade on imaging were recorded. Among 102 lymphoma patients, 34 (33.3%) were treated during the year prior vaccination with anti-CD20 antibody containing therapy. A subgroup of 54 patients also underwent serologic testing 2-3 weeks after the booster dose, and their anti-spike titers were recorded and graded as well.
Results: The overall incidence of VAHL in patients with hematologic malignancy was 31.4%. The 34 lymphoma patients treated during the year prior vaccination with anti-CD20 antibody containing therapy had significantly lower rates of VAHL comparted to all other lymphoma patients (8.8% versus 41.2% in all-PET patients, Pv < 0.01). VAHL rates were 10% in patients with negative serology, 31.3% in patients with low anti-spike titers and 72.2% in patients with high anti-spike titers. The positive predictive values of VAHL were 90% and 93.3% in all-PET and PET-2 patients, respectively. A positive statistically significant correlation was found between VAHL and serology ranks in All-PET patients (rs = 0.530, Pv < 0.001), and stronger correlation was found in PET-2 patients (rs = 0.642, Pv < 0.001).
Conclusion: VAHL on [18F]FDG PET-CT of patients with hematologic malignancy may reflect GC B-cell proliferation and an effective humoral response elicited by BNT162b2 vaccine.

Figure 1

Figure 2

Figure 3
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