Post-procedural Thyroid Cyst Infection Following Aspiration and Polidocanol Sclerotherapy: A Case Report

Ultrasound-guided aspiration and sclerotherapy are established minimally invasive approaches for the management of benign cystic and predominantly cystic thyroid nodules. Polidocanol has been reported as an effective sclerosant with a favorable safety profile, although infectious complications are rarely emphasized. We describe a 65-year-old woman with type 2 diabetes mellitus and rheumatoid arthritis who underwent ultrasound-guided aspiration of a recurrent predominantly cystic left thyroid nodule, with drainage of 33 cc of thick colloid material, intracavitary instillation of 4 cc of 3% polidocanol, and fine-needle aspiration of the residual solid component. Within 24 hours, she developed fever and systemic symptoms, initially without obvious local inflammatory signs. Over the following days, she developed painful left cervical swelling and marked sonographic re-expansion of the lesion. Repeat aspiration yielded purulent-appearing material, although only 5 cc could be drained despite multiple attempts. Laboratory testing showed a leukocyte count of 12,100/µL, total neutrophils of 9,860/µL, total lymphocytes of 1,940/µL, immature granulocytes of 0, an erythrocyte sedimentation rate of 12 mm/h, and a C-reactive protein level of 19.230 mg/dL. Gram stain demonstrated gram-positive cocci, culture grew Staphylococcus epidermidis, and anaerobic culture at seven days was negative. The patient subsequently required hospitalization for 72 hours and intravenous trimethoprim-sulfamethoxazole, with clinical improvement and reduction in cervical swelling. This case highlights a rare probable post-procedural infectious complication after aspiration and polidocanol sclerotherapy of a predominantly cystic thyroid nodule and underscores the value of early repeat ultrasound and microbiologic reassessment when persistent fever, pain, and rapid lesion re-expansion occur.