Primary Hyperaparathyroidism due to Cystic Parathyroid Adenoma not Detected on 99mTc-Sestamibi Scan

• Published in: Endocrinology and metabolism (Seoul) pp. 83 - 88
• Main Authors: 강아름, 김은기, 남은영, 변선주, 김정희, 온정헌, 홍은실, 최형진, 정경천, 성명훈, 신찬수, 박경수, 김성연
• Format: Journal Article
• Language: English
• Published: 대한내분비학회 01.03.2012
• Subjects: 내과학
• ISSN: 2093-596X; 2093-5978

Parathyroid cysts, which can be divided into functional and non-functional cysts, are rare causes of primary hyperparathyroidism. A technetium-99m-methoxyisobutylisonitrile (99mTc-sestamibi) parathyroid scan is a sensitive diagnostic tool for the localization, although it sometimes shows a false-negative result. Here we report a case of presumed cystic parathyroid adenoma based on clinical findings and analysis of cystic fluid with negative findings in a parathyroid scan. A 44-year-old male patient visited the hospital due to leg pain and compressive symptoms (dysphagia, hoarseness) that had started 4-5 months before. His serum calcium level was 14.4 mg/dL and his intact parathyroid hormone (iPTH) had increased to 478.1 pg/mL. On neck computed tomography, a cystic nodule measuring 6.2 cm was detected in the inferior part of the right thyroid gland. Sestamibi uptake for this nodule was not detected on 2-h delayed imaging, and fluorodeoxyglucose positron emission tomography showed only subtle uptake. Fine-needle aspiration was performed and intracystic iPTH had increased to 61,600 pg/mL. Focused parathyroidectomy guided by intraoperative iPTH monitoring led to successful enucleation of the right inferior parathyroid gland. A parathyroid adenoma was confirmed, and his laboratory results had normalized. This study shows that cystic parathyroid adenoma can sometimes be difficult to detect on a 99mTc-sestamibi parathyroid scan. KCI Citation Count: 0