Percutaneous Polidocanol Injection as an Alternative Treatment in Differentiated Thyroid Cancer Oligometastasis

Introduction: Differentiated thyroid cancer (DTC) presents central lymph node metastasis in 20-50% and lateral in 12-86% of patients, the treatment of choice is surgical reintervention but it carries a higher risk of complications secondary to fibrosis formation in the surgical bed. Alternative nonsurgical therapies such as percutaneous ethanol injection (PEI), radiofrequency or laser ablation have been described. Objective: To report a case of oligometastasis in CDT which underwent percutaneous polidocanol injection (PPI). Clinical Case: A 35-year-old female who underwent a total thyroidectomy in 06-2019 for papillary thyroid cancer (AJCC: stage I/ ATA: intermediate risk), and ablative dose of 150 mCi I(131), under treatment with levothyroxine 150 mcg/d. Hospitalized 02-2020 for progressive dysphonia of 2 months of evolution, with studies of TSH 0.04 mIU/ml, TgAb 13 IU/ml, Tg 0.5 ng/ml and neck USG: right lymph node level III of 0.97 cm in short axis, suspected of malignancy. Tg washout 4743.72 ng/ml (positive), 1cc of 1% polidocanol is administered, guided by USG. 7 days later with 0.90 cm in short axis, a second dose of 1% polidocanol was administered and a new Tg washout was taken, 2.4 ng/ml (indeterminate). She was reevaluated in the first and fourth months of the procedure, with 0.10 cm in the short axis and complete disappearance of the lesion, respectively. Control studies at the fourth month of TgAb 13 IU/ml, Tg 0.4 ng/ml. Discussion: PEI is described for thyroid cysts and adenomas and for cervical lymph node metastases, this is a minimally invasive procedure in the treatment of lesions smaller than 10 mm but requires multiple sessions and it can cause pain due to extravasation, skin necrosis and damage to the recurrent laryngeal nerve. It requires a follow-up time of up to 65 months, producing a reduction in serum Tg less than 2.4 ng/ml, a decrease in the size of the lesion and disappearance in 46% of the cases. In our center we have experience with PPI in thyroid cysts and adenomas since 2017, this requires fewer sessions and a lower dose, obtaining results of volume reduction in thyroid cysts of 80%. In this case we observed a reduction of 90% in the first month and disappearance in the fourth month, with a significant decrease in Tg washout from the first administration. Conclusion: Polidocanol is safe and effective so it should be considered in the treatment of oligometastasis in DTC.