A 28-year-old woman, who experienced headache and left axillary pain after the second vaccine dose, performed a US examination 2 days after that revealed the presence of enlarged (26 × 7 mm) axillary lymph nodes with preserved fatty hilum, thickened cortex (5 mm) and increased vascularization at color-Doppler. A pathological ipsilateral sub-clavicular lymph node (33 × 11 mm) was also found with no visible fatty hilum and increased vascular signal (Fig. ). In both nodes, shear-wave elastography showed a soft texture (mean values between 13 and 18 kPa). No pathological lymph nodes were found in lymph node stations contralateral to the site of vaccine injection. The patient had previously undergone a breast US for a routine control after receiving the first vaccine dose, that did not show any significant abnormalities.
US examination was performed in a 33-year-old woman with the occurrence of axillary pain and a palpable lump in the supraclavicular region 8 days after the first dose of Pfizer-BioNTech vaccine. The patient had also experienced fever and fatigue right after vaccine injection. Both axillary and supraclavicular lymph nodes were found enlarged (maximum diameter 14 × 6 mm), with no fatty hilum, increased vascularization and soft-intermediate consistence at shear-wave sonoelastography (Fig. ). No pathological lymph nodes were found in the contralateral axilla. US lymph node features were substantially stable at US examinations performed after 3 weeks.