Exp Clin Endocrinol Diabetes 2015; 123 - P01_07
DOI: 10.1055/s-0035-1547621

Three cases of primary hyperparathyroidism caused by a parathyroid cyst

P Kirchner 1, L Rados 2
  • 1Universitätsklinik; Med Klinik 1; Endokrinologie
  • 2Universitätsklinik; Inselspital; Innere Medizin

Background/Introduction: We describe 3 cases of functional parathyroid cyst with different clinical presentation.

Methods: Case 1: A 21 year old recruit reported dysphagia, swelling and pulsation of the neck after physical activity. Ultrasound of the neck has shown a cyst of 6 cm. The cytological examination after aspiration did not reveal the origin of the cyst. We confirmed a mild parathormone-mediated hypercalcemia without symptoms. Genetic analysis for MEN-1 mutation was negative.

Case 2: A 72 year old woman suffered from four different fractures within the last several years after repeated falls caused by muscle weakness. After surgery due to a forearm fracture a preexisting decline in cognitive function worsened and she had to be referred to the psychiatric clinic. A severe parathormone-mediated hypercalcemia of 13.8 mg/dl was diagnosed. Ultrasound has shown a cyst of 2.5 cm in diameter close to the thyroid gland.

Case 3: A similar ultrasound finding was observed in a 52 year old woman after the accidentally diagnosis of a milde parathormone-mediated hypercalcemia while a routine blood sample.

Results: In all cases the fractionated calcium excretion was above 2% and hypercalcemia was caused by primary hyperparathyroidism. The level of PTH in the cyst fluid after FNA was > 5000 pg/ml and confirmed the origin of the cyst to the parathyroid gland in case 1 and the reason for the severe hypercalcemia in case 2. In case 3 the activity of the parathyroid cyst was confirmed by a 99 mTc sestamibi scintigraphy. The intraoperative drop of PTH by more than 50%, the histological result of hyperplastic parathyroid tissue and the normalization of hypercalcemia after surgery confirmed the diagnosis in each case.

Conclusion: A functional parathyroid cyst may present with local symptoms, symptomatic or asymptomatic hypercalcemia. FNA and determination of PTH in the aspirate is an easy and reliable tool to localize the functional parathyroid tissue in these rare cases of primary hyperparathyroidism. This assessment may be helpful to differentiate the origin of cystic neck lesions also in patients without primary hyperparathyroidism.