SEVERE HYPERCALCEMIA UNMASKS A CAMOUFLAGED PARATHYROID CARCINOMA

Abstract

INTRODUCTION/BACKGROUND
Parathyroid carcinoma is an exceedingly rare endocrine malignancy and an uncommon cause of primary hyperparathyroidism. We report a case of severe hyperparathyroidism which required urgent surgery and unveiled a parathyroid carcinoma.

CASE
A 31-year-old Malay female, who initially presented with severe epigastric pain and vomiting, was treated for acute pancreatitis in the surgical ward. There was no history of alcohol consumption. Biochemistry results showed acute renal impairment, hypercalcemia (corrected Ca2+ 4.06 mmol/L), hypophosphatemia (PO43- 0.38 mmol/L), elevated serum amylase (370 U/L) and urine diastase (663 U/L). However, no sonographic evidence of cholelithiasis was found. She was referred to the medical team for further investigations which revealed primary hyperparathyroidism with vitamin D deficiency (iPTH 705 pg/ml, 25 (OH) vitamin D 25 nmol/L, alkaline phosphatase 543 U/L). Clinically, no neck mass was observed but the neck detected a TIRADS 5 nodule in the right thyroid. Given the discordant clinical and sonographic findings, Tc99m Sestamibi SPECT/CT was arranged but she defaulted. Subsequently, she was admitted for severe hypercalcemia manifesting as severe bone pain and requiring salineforced diuresis and intravenous zolendronic acid. Tc99m Sestamibi SPECT/CT scan demonstrated a parathyroid adenoma measuring 2.2 x 2.6 x 2.9 cm posterior to the right thyroid gland. Further imaging work-up showed bilateral medullary nephrocalcinosis and osteopenia. She underwent urgent right hemithyroidectomy, right superior parathyroidectomy and central neck dissection successfully. Postoperatively she developed hungry bone syndrome which required intravenous calcium infusion together with high dose activated vitamin D and calcium supplements. Histopathological report confirmed the diagnosis of parathyroid carcinoma with lymphovascular and capsular invasion. Postoperatively she was scheduled for PET-CT scan but she defaulted the follow-up. She is currently pregnant.

CONCLUSION
Parathyroid carcinoma is an indolent but progressive disease. Surgery is the mainstay of treatment. Early detection with attempts to remove local recurrence and distant metastasis can provide good short- and long-term control.