A RARE CASE OF RECURRENT PARATHYROID CARCINOMA

Abstract

INTRODUCTION/BACKGROUND
One of the rare causes of primary hyperparathyroidism is parathyroid cancer. It is usually diagnosed postoperatively with histopathology. Surgery is always definitive in parathyroid carcinoma, but there have been reported recurrences of parathyroid cancer up to 20 years after a successful surgery. We report a case of a 61-yearold male who had bilateral inferior parathyroid carcinoma, surgically cured in 2020, but had a recurrence of parathyroid carcinoma after 3 years.

CASE
A 54-year-old male presented with headaches and dizziness and was suspected of having had a stroke. Further investigations revealed that the patient had primary hyperparathyroidism, with a corrected calcium level of 3.56 mmol/L (normal range 2.1-2.55), a phosphate level of 0.93 mmol/L (normal range 0.74–1.52), and an iPTH level of 148.28 pmol/L (normal range 1.59–7.24). Thyroid ultrasound detected a bilateral enlarged inferior parathyroid gland measuring 1.5 x 1.3 cm and 1.6 x 1.3 cm, and a SESTAMIBI scan confirmed the presence of parathyroid hormone hypersecretion. He underwent a successful bilateral inferior parathyroidectomy, and a histopathological examination revealed parathyroid carcinoma. He remained normocalcaemic, but his iPTH levels increased with time, from 12.05 pmol/L to 30.23 pmol/L. A subsequent ultrasound of the thyroid showed a tiny extra-thyroidal lesion adjacent to the left internal jugular vein, and a repeat SESTAMIBI scan revealed concordant parathyroid hypersecretion over the left superior thyroid gland. However, a neck CT scan failed to locate the lesion. Parathyroid carcinoma is commonly related to Multiple Endocrine Neoplasia (MEN Syndrome) and familial isolated hyperparathyroidism. 4D CT, MRI, and hybrids of SESTAMIBI and CT/MRI enable more precise localization of ectopic disease glands.

CONCLUSION
It is important to have lifetime surveillance for parathyroid carcinoma survivors, as the recurrence rate is high despite surgery, with a mean survival of 6-7 years.