ABSTRACT
Background-Aim: 18F-FDG PET/CT currently represents the nuclear medicine imaging procedure of choice for staging and posttreatment response assessment in patients with Hodgkin lymphoma (HL). It is well known that 18F-FDG also accumulates in sites of inflammation and infection. Here we report a case of a patient affected by lung HL and concomitant incidental COVID-19 interstitial pneumonia. Methods: The case refers to a 67 years old female patient affected by nodular sclerosing classical HL involving left axillary lymph nodes and both lungs. The patient came to our attention to perform wholebody 18F-FDG PET/CT at initial staging (scan 1), after two cycles of ABVD (scan 2) and at the end of treatment (scan 3). All 18F-FDG PET/CT examinations were performed according to standard acquisition protocols, starting approximately 60 min after i.v. injection of 3.7 MBq/kg of 18F-FDG. Results: At scan 1, 18F-FDG-PET/CT showed hypermetabolic left axillary lymph nodes and multiple disseminated avid lesions in both lungs. Scan 2 demonstrated complete metabolic response associated to almost complete resolution of axillary lymphadenopathy and lung lesions at CT scan. At the end of treatment, scan 3 showed hypermetabolic mediastinal lymph nodes and multiple areas of increased 18F-FDG uptake in both lungs, mostly in pulmonary regions other than those of the basal scan, and in correspondence of multiple ground-glass opacities and consolidations at CT. These findings were more suggestive for interstitial pneumonia than for HL residual disease;in addition, contrast-enhancement CT performed 1 week before scan 3, resulted completely negative. Given the ongoing SARS-CoV- 2 pandemic, the patient, although asymptomatic, was scheduled to perform nasopharyngeal molecular swab test for COVID-19;the test resulted positive, corroborating the hypothesis of early interstitial pneumonia. The patient was clinically monitored and 3 months later underwent a further 18F-FDG PET/CT scan which was negative, definitively confirming the absence of lymphomatous disease. Conclusions: In this patient affected by lung HL, an incidental early COVID-19 pneumonia was detected by 18F-FDG PET/CT. The comparison of basal and post-treatment PET/CT scans in combination with lung CT patterns have led to a correct assessment of chemotherapy response.
ABSTRACT
Background-Aim: The aim of the present study was to investigate the occurrence and characteristics of axillary lymph node hypermetabolism (ALNH) after COVID-19 vaccination in a large series of cancer patients undergoing 18F-FDG PET/CT. Methods: We retrospectively reviewed a consecutive series of 500 cancer patients (267 males and 233 females, aged 22-91 years, mean age: 64.9 years) who underwent 18F-FDG PET/CT after COVID-19 vaccination (period: March-October 2021). Twenty of these patients were studied twice for a total of 520 PET/CT studies;135/520 studies were carried out after the first dose of vaccine and the remaining 385/520 studies after the second dose. All FDG PET/CT studies were acquired at the same nuclear medicine Centre according to standardized acquisition procedure protocols, using a Discovery 710 system (GE Healthcare). PET images were analysed both qualitatively and semiquantitatively calculating SUV max at the level of hypermetabolic lymph nodes. Results: ALNH ipsilateral to COVID-19 vaccination was observed in 176/520 studies (33.8%). Among the 176 positive studies, HALN was considered vaccine-related (Group 1) in 130/176 cases (74%), metastatic (Group 2) in 34/176 cases (19.3%) and equivocal (Group 3) in the remaining 12/176 cases (6.8%). SUV max was 3.5 ± 2.21 in Group 1, 8.95 ± 5.83 in Group 2 and 3.912 ± 1.66 in Group 3 (p<0.0001). Among the 130 Group 1 cases, 31 were studied after vaccine dose 1 (subgroup 1A) and 99 after vaccine dose 2 (subgroup 1B) with SUV max equal to 3.12 ± 1.72 in the former subgroup and 3.62 ± 2.34 in the second subgroup (p = 0.27). Furthermore, in the subgroup 1A, SUV max was 3.68 ± 2.01 in the first week after vaccination, 2.76 ± 1.57 in the second week and 2.52 ± 1.2 in the third week (p = 0.567), while in the subgroup 1B the corresponding SUV max values were 5.51 ± 3.03, 3.81 ± 2.01 and 3.17 ± 1.96 (p<0.001). After third week post-vaccination, FDG lymph node avidity was observed in 2/31 subgroup 1A cases and in 27/99 subgroup 1B cases. Conclusions: In our series, the overall prevalence of vaccine-related ALNH was 25% (130/520). Vaccine-related hypermetabolic lymph nodes showed a significantly lower SUV max than that observed in metastatic lymph nodes. Equivocal findings were seen in<7% of cases. No statistically significant difference in SUV max was seen after dose 1 and dose 2 vaccinations. However, after the second vaccination, the SUV max was statistically higher in the first week rather than later. Finally, FDG lymph node uptake may persist beyond the third week, mainly after the second vaccination.