Endocrinol Metab > Volume 27(1); 2012 > Article
Endocrinology and Metabolism 2012;27(1):83-88.
DOI: https://doi.org/10.3803/EnM.2012.27.1.83    Published online March 1, 2012.
Primary Hyperaparathyroidism due to Cystic Parathyroid Adenoma not Detected on 99mTc-Sestamibi Scan.
Ah Reum Khang, Eun Ki Kim, Eun Young Nam, Sun Ju Byeon, Jung Hee Kim, Jung Hun Ohn, Eun Shil Hong, Hyung Jin Choi, Kyeong Cheon Jung, Myung Whun Sung, Chan Soo Shin, Kyong Soo Park, Seong Yeon Kim
1Division of Endocrinology and Metabolism, Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea. csshin@snu.ac.kr
2Department of Pathology, Seoul National University College of Medicine, Seoul, Korea.
3Department of Otorhinolaryngology, Seoul National University College of Medicine, Seoul, Korea.
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.
Key Words: Hyperparathyroidism, Parathyroid neoplasms, Technetium Tc 99m sestamibi

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