Abstract
Introduction: Parathyroid carcinoma is a rare malignancy that can be difficult to diagnose due to clinical features shared with benign primary hyperparathyroidism (PHPT). It accounts for 1% of PHPT cases and has symptoms commonly referred to as “bones, stones, abdominal moans, and psychic groans,” attributable to hypercalcemia, elevated parathyroid hormone (PTH), nephrolithiasis, cognitive dysfunction, insomnia, fatigue, and bone demineralization. Compared with benign PHPT, parathyroid carcinoma can present with more pronounced elevation of calcium and PTH, as well as a palpable neck mass that is rare in benign HPT. Complete, negative-margin resection is the standard of care. Because of its rarity, there is currently no consensus on the Tumor, Node, Metastasis (TMN) staging of parathyroid carcinoma. Purpose: The purpose of this presentation is to update Advanced Practice Providers (APPs) on the diagnosis, evaluation, management, and oncologic surveillance of parathyroid carcinoma. Discussion: Case: A 48 year old woman presents with fatigue, constipation, and bone pain. Evaluation revealed a serum calcium of 14.2, prompting a PTH measurement which was elevated at 312. Localization of a presumed parathyroid adenoma was completed. Sestamibi scan and ultrasound of the neck revealed a large left inferior parathyroid adenoma. The patient underwent a parathyroidectomy with an en bloc resection left lobectomy, excision of sternocleidomastoid muscle, and a few surrounding lymph nodes. Pathology revealed parathyroid carcinoma. Given the malignancy findings, a staging CT scan followed which did not reveal metastasis. She was evaluated every 6 months with a calcium and PTH level. Her levels remained normal until 2 years post-operatively when her calcium was elevated at 11.9 and subsequent Neck CT revealed cervical adenopathy. She was then referred to a high-volume cancer center where biopsy confirmed recurrent disease in the left neck and superior mediastinum, and she underwent lymphadenectomy. Unfortunately, she later presented with metastasis to the liver. This case will be presented to elucidate the unique features of parathyroid carcinoma along with its diagnosis and management. Conclusion: Parathyroid carcinoma is rare, but it is vital for APPs to be knowledgeable of its appropriate evaluation and management as recurrence and persistent disease can be a problem in more than 50% of patients. It is important to be well-informed in order to manage, counsel, and refer patients appropriately. Much work is needed towards formulating a TMN staging system to guide treatment. Accurate diagnosis, pathological evaluation, and surgical documentation is vital to long term development of a staging system.
