Endocrine Abstracts

Introduction: Multiple endocrine neoplasia type 2A syndrome (MEN 2A) is caused by a germline mutation in the RET proto-oncogene and its phenotype includes medullary thyroid cancer, pheochromocytoma and primary hyperparathyroidism (PHPT). Parathyroid reimplantation in the sternocleidomastoid muscle or in the brachioradial muscle can be performed in case of intraoperative lesion of the parathyroid glands. In some cases, PHPT may occur due to the proliferation of autotransplanted parathyroid tissue, which may hinder its diagnosis.

Case report: Female patient, 55 years old, with personal and family history of MEN2A, with medullary thyroid carcinoma, but no evidence of pheochromocytoma or PHPT. She underwent total thyroidectomy for medullary thyroid carcinoma and remained under surveillance and in remission for 20 years (levels of calcitonin, PTH, serum calcium and plasma metanephrines within the normal range). Afterwards, she developed PTH-dependent hypercalcemia, with serum calcium of 11.1 mg/dl (8.6–10.5 mg/dl), PTH 194.3 pg/ml (12–67 pg/ml) and 24 h urine calcium of 430 mg (80–300 mg). A cervical ultrasound was performed, which showed a 20 mm nodule, anterior to the right sternocleidomastoid muscle and a parathyroid scintigraphy, which described a moderate uptake in the right lateral cervical region, raising questions regarding its etiology. We reviewed the patients’ medical charts and found out that the surgical team performed an autotransplantation of the right lower parathyroid in the sternocleidomastoid muscle at the same time of the thyroidectomy, due to likely intraoperative lesion of the parathyroid glands. We decided to perform a fine needle aspiration biopsy of the nodule, which was compatible with parathyroid tissue and PTH measurement in needle washout, which was 33 363 pg/mL. She underwent parathyroidectomy and the histological report was compatible with parathyroid adenoma. The patient is currently in remission, with serum calcium of 8.8 mg/dl and PTH 63.6 pg/ml.

Discussion: Patients with MEN2A who develop PHPT after thyroidectomy and parathyroid gland autotransplantation might be a diagnostic challenge. At reoperation, only enlarged parathyroid glands should be excised. This is a rare case that highlights the importance of clinical evaluation and preoperative localization imaging tests as well as long-term survellaince of serum calcium and PTH levels.