Abstract
Abstract Introduction Parathyroid carcinoma is a rare endocrine malignancy, accounting for a small fraction of primary hyperparathyroidism (PHPT) cases. Its rarity complicates diagnosis due to overlapping symptoms with benign conditions and challenges in pathological examination. Limited cases result in insufficient data on optimal treatment strategies and outcomes. Clinical Case A 49-year-old male with a history of symptomatic primary hyperparathyroidism (PHPT) four years earlier was referred due to recurring hypercalcemia. His initial imaging scans were unobtainable, however, he had a pathology report indicating that he had total thyroidectomy, left-sided cervical lymph node dissection (LND) and parathyroidectomy. A poorly differentiated thyroid carcinoma measuring 4.5x3.5 cm with positive surgical margins and cervical lymph node metastases (15/24) were reported. Additionally, three parathyroid glands were excised; with one reported to be a parathyroid adenoma with a Ki-67 index of 7-10%. The patient was asymptomatic for the following 4 years, except for a transient hypocalcemia early after surgery. However, recently, his symptoms of nausea, muscle weakness and fatigue returned due to recurrent PHPT. Two months before being referred to our center, he was assessed elsewhere (Serum Ca: 15.6 mg/dL, P: 1.9 mg/dL, creatinine: 1.2 g/dL, PTH: 1121 pg/mL), and given 5 mg intravenous zoledronic acid, followed by cinacalcet 30 mg daily. At the time of his presentation to our center, physical examination was unremarkable except surgical scars compatible with thyroidectomy and left-sided cervical LND, and a fixated left-sided supraclavicular lymph node of ∼2 cm. Upon presentation at our center, his labs showed Calcium: 12.07 mg/dL, phoshorus: 1.63 mg/dL, PTH: 1319 pg/mL, and imaging revealed multiple metastatic lymph nodes and lung metastases. A pathology re-evaluation confirmed parathyroid neoplasia, as the immunohistochemical evaluation of the specimens were positive for PTH but negative for thyroidal markers. Multidisciplinary treatment included cervical LND, surgical removal of lung and pleura metastases for reducing tumor load, followed by denosumab, and 16 cycles of paclitaxel and carboplatin, achieving stable disease. Sorafenib was then administered and continued for 18 months. The patient has an 8-year overall survival, with rather stable PTH levels (909-1626 pg/mL), with recent rapid PTH progression to 7897 pg/mL. Conclusion Management of parathyroid carcinoma requires a multidisciplinary approach, with a focus on meticulous metastatic assessment and calcium control. Surgical excision is advised for regional recurrences, while surgery for distant metastases is mainly palliative. Though rare, multikinase inhibitors may help manage hypercalcemia, but long-term survival data are lacking, warranting further research.
Published Version
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