Endocrine Abstracts

Introduction: The basis of treatment of primary hyperparathyroidism (pHPT) is parathyroidectomy of the responsible lesion, and thus, preoperative localization is important. Ectopic parathyroid adenomas are rare, and they can be accounted for persistent or recurrent hyperparathyroidism. An intrathyroidal parathyroid adenoma (IPA) is an ectopic variant where the adenoma is either partly (>50%) or completely enveloped by the thyroid gland. The incidence of IPAs ranges from 0.7% to 6%. We herein report two cases of primary hyperparathyroidism due to intrathyroidal parathyroid adenomas (IPA).

Case presentation: The first patient, a 60-years-old woman, was referred to our clinic for hypercalcemia. She was not experiencing any symptoms of hypercalcemia. The laboratory investigations showed an elevated serum calcium level of 12 mg/dl (normal range: 8.5–10.2) and parathyroid hormone level of 148.3 pg/ml (normal range: 15–45). The anterior cervical ultrasound revealed an intense hypoechoic, homogenous, with well-defined margins mass of 17/15 mm localized in the right thyroid lobe. A fine needle aspiration with PTH washout was performed indicating a PTH level of 2213 pg/ml. She underwent surgery and postoperative levels of calcium and PTH normalized. The histopathological evaluation confirmed the diagnosis of parathyroid adenoma. The second patient, a 30-year-old male, with history of autosomal dominant tubulointerstitial kidney disease and renal transplant, was admitted for a routinely endocrinological check−up. His laboratory results showed a serum calcium level of 11.5 mg/dl and a parathyroid hormone level of 200.5 pg/ml (normal range: 15–45). A homogenous, clear borderline, hypoechoic mass of 21.5/5.6 mm located in the left thyroid lobe was found at the neck ultrasound. The ⁹⁹mTc−estamibi scintigraphy did not find images suggestive of parathyroid adenomas, but fine needle aspiration with PTH washout from the intrathyroidal nodule revealed a PTH of 1215 pg/ml, which confirmed the parathyroid origin of the nodule. He is scheduled to undergo a left hemithyroidectomy.

Conclusion: It is difficult to make a definitive diagnosis of IPA before surgery, although the accuracy of diagnosis of IPA can be increased by combining various techniques, such as imaging and fine needle aspiration biopsy. The optimum technique likely depends on a variety of patients, surgeons, and center-dependent factors. The presented cases had completely enveloped parathyroid adenomas, one was cured after surgery and the other will undergo the same treatment. A thorough search for other adenomas and at other ectopic sites before thyroid lobectomy is associated with higher success rates.