Non-functional parathyroid cyst--diagnostic pitfall: A case-report

Parathyroid cysts are relative rare and they may be misdiagnosed with thyroid nodules. Parathyroid cysts are characterized by elevated level of parathyroid hormone (PTH) in cystic fluid. CASE REPORT. We reported about middle-aged woman with palpable node in the left thyroid lobe. Ultrasound showed anechoic 40 x 25 mm lesion in the left thyroid lobe. Fine needle aspiration (FNA) obtained 13 mL colorless, watery cystic fluid. PTH value in cystic fluid was ten fold more in comparison with serum PTH. Serum PTH was slightly elevated, D vitamin was under the reference range, serum calcium and phosphorus were normal as well as thyroid hormones. Thyroglobulin antibodies (TgAb) and thyroid peroxidase antibodies (TPOAb) were not detected. Radionuclide parathyroid scintigraphy indicated at physiological metaiodbenzyl-guamidine (MIBG) distribution. After six monthsof vitamin D supplementation, serum calcium, phosphorus, vitamin D and PTH were normal. This finding was indicative that was a nonfunctional parathyroid cyst.

This case report points out that thyroid cystic lesions with thin walls, and reverberation in ultrasound, must be observed as a potential parathyroid cyst. These cysts require caution during diagnostic aspiration because of danger of hypercalcemic crises due to FNA, which can be a life-threatening condition.