A Middle-aged Woman With Recurrent Intrathyroidal Parathyroid Cyst Treated With Ethanol Sclerotherapy

Background/Objective: Parathyroid cysts (PC) are a rare cause of cervical masses, with an ectopic intrathyroidal location being even more rare, with only 9 cases reported in the literature. We present a case of a recurrent intrathyroidal cyst successfully treated with ethanol sclerotherapy. Case Report: A 64-year-old woman presented to our clinic in 2017 with a cervical prominence and recurrent pressure sensation in her left lower neck. She had a history of multiple cyst aspiration drainage procedures for a recurrent intrathyroidal PC. Ultrasound revealed a simple cyst measuring 5.1 cm × 2.1 cm × 1.7 cm encompassing most of the left thyroid lobe. Parathyroid hormone level in the cyst fluid was elevated, but serum calcium and parathyroid hormone levels were within normal range. To prevent additional recurrences, ethanol sclerosis of the cyst was performed. After 6 years of follow-up, the patient remains asymptomatic and without evidence of PC recurrence. Discussion: Although surgical resection of PC can be performed, in the case of an intrathyroidal PC, this would involve loss of functional thyroid tissue and the potential risk of postoperative hypothyroidism. Ethanol sclerosis has been successfully utilized to shrink both thyroid cysts and orthotopically positioned PCs while preserving thyroid tissue. In this case, ethanol sclerosis was used to successfully manage an intrathyroidal PC. Conclusion: Based on the excellent response in this case and reports of efficacy of sclerosis in orthotopically positioned PCs, we conclude that ethanol sclerotherapy seems to be an effective treatment option for recurrent intrathyroidal PCs.