Enlargement of a metastatic lymph node from differentiated thyroid cancer after COVID-19 vaccination

BACKGROUND: The massive vaccination campaign against COVID-19 has granted a high level of protection against the severe forms of the disease at the price of some mild adverse events. OBJECTIVE: To underline that COVID-19 vaccination can induce a transient enlargement of lymph-node metastases in differentiated thyroid cancer patients. CASE PRESENTATION: We describe the clinical, laboratory, and imaging features of a 60-year-old woman affected by paratracheal lymph-node relapse of Hurtle Cell Carcinoma who came to our attention after full COVID-19 vaccination because of neck swelling and pain. In April 2021, after 5 years of stable structural disease, the patient presented an enlargement of the metastatic lymph node, associated with a rise of serum thyroglobulin (from 4.6 to 14.7 pg/mL). Anti-inflammatory treatment was started and pain and swelling remitted after 15 days. At the subsequent evaluation, at neck ultrasound, the right paratracheal lesion was smaller and thyroglobulin dropped to 3.9 pg/mL. CONCLUSIONS: We report the case of an enlargement of metastatic lymph node from differentiated thyroid cancer after COVID-19 vaccination. We warn clinicians to identify features of inflammatory response due to COVID-19 vaccination in order to prevent unwarranted surgical treatment.