Axillary Lymphadenopathy After Coronavirus Disease 2019 Vaccinations in Patients With Thoracic Malignancy: Incidence, Predisposing Factors, and Imaging Characteristics

Abstract

Objectives: Axillary lymphadenopathy from coronavirus disease 2019 (COVID-19) vaccine is an emerging phenomenon during unprecedented mass vaccinations, which can be incidentally found on computed tomography (CT) scans. This study investigated the incidence, predisposing factors, and imaging characteristics of vaccine-related axillary lymphadenopathy in patients with thoracic malignancy who underwent CT scans before and after COVID-19 vaccinations.

Methods: The study included patients with thoracic malignancies who received two doses of mRNA-based COVID-19 vaccinations and had prevaccine and postvaccine chest CT scans. Postvaccine chest CT scan results were reviewed for increase in size of lymph nodes in the axilla and subpectoral areas, comparing with the prevaccine scan results. The cases with lymphadenopathy were further reviewed independently by two radiologists referring to clinical information to find whether lymphadenopathy was attributed to the vaccinations.

Results: Vaccine-related axillary lymphadenopathy was noted in 21 of 232 patients (9.0%). The median short-axis diameter of the largest node was 7 mm (range: 5-14 mm). The median number of increased nodes was 4 (range: 1-10). The median time to the postvaccine scan revealing lymphadenopathy was 1.7 weeks (range: -2.9 to 6.6) from the second dose. Vaccine-related lymphadenopathy was noted more often in women than in men (18 of 144, 12.5% versus 3 of 88, 3.4%, respectively; p = 0.019) and with mRNA-1273 vaccines than BNT162b2 vaccines (6 of 28, 21% versus 15 of 204, 7.4%, respectively; p = 0.026).

Conclusions: The incidence of lymphadenopathy was 9%, with a median onset time of 1.7 weeks after the second vaccine dose. Female sex and vaccine type (mRNA-1273 vaccine) were associated with higher frequency of lymphadenopathy, providing initial observations to inform further investigations in larger cohorts.

Keywords: COVID-19; Computed tomography; Lymphadenopathy; Vaccinations; mRNA vaccine.

Figure 1

COVID-19 vaccine-related axillary and subpectoral lymphadenopathy on CT and FDG-PET/CT. Patient A. A 67-year-old woman with SCLC who received two doses of COVID-19 vaccine in the left deltoid and underwent a prevaccine CT (4.4 wk before the first dose) and a postvaccine CT (0.6 wk after the second dose) for tumor surveillance. Postvaccine CT results revealed increased lymph nodes in the left axilla (A2, white arrow) and the subpectoral region measuring up to 14 mm in the short axis (A2, yellow arrows), compared with the prevaccine CT results (A1, arrows). There was no increase of other thoracic nodes or lung lesions on the chest CT. The patient underwent PET/CT at the outside institution 7 weeks after the postvaccine CT, which reportedly revealed decrease of these nodes without FDG uptake (the images are not available and not illustrated). Patient B. A 57-year-old woman with stage IV NSCLC undergoing systemic therapy who received two doses of COVID-19 vaccine in the left deltoid and underwent a prevaccine CT (8.7 wk before the first dose) and a postvaccine CT (0.3 wk after the second dose) for treatment monitoring. Postvaccine CT results revealed increase of the left axillary and subpectoral lymph nodes (B2, white oval) measuring up to 8 mm in the short axis, compared with the prevaccine CT results (B1). The CT scan results otherwise revealed stable disease without new or increasing lesions. Patient C. A 52-year-old man with stage IV NSCLC who received two doses of COVID-19 vaccine in the left deltoid and underwent a prevaccine CT (4.4 wk before the first dose), PET/CT between two doses (3.4 wk after the first dose), and CT after the second dose (3.6 wk after the second dose) for tumor surveillance. Postvaccine PET/CT results revealed an increased left axillary lymph node with FDG uptake (SUV_max: 2.2) (C2, arrows), compared with the prevaccine CT results (C1). The PET/CT results revealed tumor response to therapy with decreased right lower lobe lesion, without any other FDG-avid lymph nodes. COVID-19, coronavirus disease 2019; CT, computed tomography; FDG, ¹⁸F-fluorodeoxyglucose; PET, positron emission tomography; SUV_max, maximum standardized uptake value.