Introduction. 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 ? 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 months of vitamin D
supplementation, serum calcium, phosphorus, vitamin D and PTH were normal.
This finding was indicative that was a nonfunctional parathyroid cyst.
Conclusion. 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.