Endoscopic ultrasound-guided ethanol ablation for mediastinal parathyroid adenoma complicated by recurrent laryngeal nerve injury: a case report

Surgery remains the first-line treatment for primary hyperparathyroidism; however, ethanol or radiofrequency ablation has emerged as an alternative treatment [ 1 ] [ 2 ]. We present the case of an 86-year-old woman with parathyroid hormone levels of up to 1,269 pg/mL. Scintigraphy identified an ectopic mediastinal adenoma ([ Fig. 1 ]). Endoscopic ultrasound (EUS) demonstrated a homogeneous lesion measuring 3 × 1.5 × 1.5 cm ([ Fig. 2 ]) with an estimated volume of 3.5 mL [ 3 ]. The lesion was hypervascular on Doppler imaging, confirmed by contrast-enhanced EUS (CE-EUS), which was used to monitor the ablation. Elastography and histological confirmation were not performed due to typical imaging findings, the need for treatment, and the patient's advanced age. Fig. 1 Scintigraphic imaging demonstrating a solitary ectopic mediastinal parathyroid adenoma located at the level of the third thoracic vertebra. Fig. 2 An endoscopic ultrasound image showing an oval-shaped mediastinal parathyroid adenoma measuring approximately 3 × 1.5 cm, surrounded by a thin capsule. As the patient preferred minimal-invasive treatment with possible side effects, EUS-guided ethanol ablation was performed, as previously described [ 4 ]. Following puncture with a 19-gauge needle pre-flushed by ethanol, 3.5 mL (the volume of the lesion) of 96% ethanol was administered in small aliquots. A characteristic ethanol-induced hyperechoic blush was observed ([ Video 1 ]). The needle was kept in situ for 2 minutes to facilitate intratumoural distribution. A two-session ablation was planned to minimise ethanol leakage. No adverse events occurred, and the parathyroid hormone levels decreased significantly. Download Video Endoscopic ultrasound-guided ethanol ablation for mediastinal parathyroid adenoma.Video 1 At follow-up, CE-EUS revealed a non-enhancing necrotic area with residual adenomatous tissue measuring 1.5 × 1.5 cm ([ Fig. 3 ]). A second ablation was performed using 4 mL of ethanol ([ Fig. 4 ]). Fig. 3 Contrast-enhanced endoscopic ultrasound performed 4 weeks after the initial ablation. A round, hypoechoic, non-enhancing (avital) area is visible in the distal portion of the tumour, consistent with necrosis, while residual viable adenomatous tissue persists in the cranial portion. Fig. 4 Endoscopic ultrasound-guided repeat ethanol ablation of the residual lesion. Injection of ethanol results in the characteristic intralesional hyperechoic blush. Parathyroid hormone and serum calcium levels normalised, and CE-EUS confirmed complete necrosis ([ Fig. 5 ]). The patient developed temporary dysphagia with aspiration due to unilateral recurrent laryngeal nerve injury with residual vocal cord hypomobility. Fig. 5 Contrast-enhanced ultrasound following the second ablation demonstrating the complete non-enhancement of the lesion, consistent with total tumour necrosis. EUS-guided ethanol ablation is a therapeutic alternative, although nerve injury is a potential adverse event. Repeated treatment is feasible [ 5 ]. We recommend a single puncture, ethanol dosing based on tumour volume, slow injection, and maintaining the needle in situ to facilitate intratumoural distribution. Endoscopy_UCTN_Code_TTT_1AS_2AG Publication History Article published online: 07 May 2026 © 2026. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution License, permitting unrestricted use, distribution, and reproduction so long as the original work is properly cited. (https://creativecommons.org/licenses/by/4.0/). Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany