Endocrine Abstracts

Primary hyperparathyroidism is the third most common endocrine disorder, caused, in the majority of cases, by a single parathyroid adenoma and rarely by multigland adenoma or parathyroid carcinoma. Giant parathyroid adenomas, defined as larger than 3 g, represent an uncommon cause of primary hyperparathyroidism, with only a few cases described in the literature. We present the case of a 47 years old female who presented with a significant, unpainful, left cervical mass associated to light symptoms of fatigue, minor polyuria and hypercalcemia >3 mmol/l. Hormonal testing revealed very important elevation of parathyroid hormone, low phosphatemia and hypercalciuria, with preserved renal function. Ultrasound of the cervical region found a nodular, solid lesion, hyperechoic with hypoechoic areas and multiple microcysts measuring 7.6 cm of greatest diameter, in contact with the inferior pole of the left thyroid lobe. 99Tc sestamibi scan was positive for a voluminous inferior left-sided, hyperfunctioning parathyroid adenoma. CT scan confirmed the mass and described a right deviation of the trachea. Fine needle aspiration found cellularity compatible with parathyroid tissue. After controlling calcium levels, surgery was performed, consisting of removal of the mass as well as the left thyroid lobe attached to it. The parathyroid lesion measured 9×6, 3×3, 5 cm and weighted 80 g. Histological diagnosis was challenging because of relative capsule invasion and demanded second opinion to finally conclude in favor of a benign adenoma. Early postoperative calcium and active vitamin D supplementation was necessary to keep normal calcium levels. Parathyroid adenomas weighing more than 70 g are extremely rare. Our patient presented the second biggest giant parathyroid adenoma described to date. Surpisingly, despite its dimensions, this giant parathyroid adenoma did not cause severe hypercalcemic or local pressure symptoms. Differential diagnosis with a parathyroid carcinoma represented the greatest difficulty prior to surgery, as well as histologically due to several overlapping characteristics.

Keywords: primary hyperparathyroidism, giant parathyroid adenoma, cervical mass, hypercalcemia, parathyroid carcinoma