A 41 year old Samoan gentleman presented with three days of abdominal pain. On examination he was dehydrated and had a fixed, hard left-sided neck swelling.

Investigations:

Bloods: cCa 5.14mmol/L (iCa 2.57mmol/L), Cr 439μmol/L, eGFR 13, PTH 302.3pmol/L (1.6-6.9)

ECG: shortened QTc (377ms) and changes mimicking ST elevation

Imaging: Subperiosteal resorption of the acromio-clavicular bones, brown tumours of the pelvis.  Neck ultrasound demonstrated a large hypervascular mass within the left thyroid lobe.

The patient was initially managed with intravenous hydration, frusemide and calcitonin.  Bisphosphonate therapy was deferred due to severe renal failure. The calcium level continued to rise, peaking at 6.1mmol/L, 36 hours after presentation.  Whilst preparing for haemofiltration the patient had three successive cardiac arrests (ventricular fibrillation).  After 12 hours of continuous filtration the calcium remained at 5.49mmol/L. SestaMIBI scanning revealed an avid lesion in the left thyroid lobe upper pole.  An emergency parathyroidectomy was performed 48 hours from his admission after four further cardiac arrests.

A large parathyroid nodular mass (70g) was removed intraoperatively.  Histopathology was suggestive of a parathyroid carcinoma with thick fibrous bands throughout and a high mitotic rate. 

Post-operatively, the PTH level dropped to 11.6pmol/L. The calcium level gradually decreased requiring calcium and calcitriol supplementation on discharge from hospital.

Parathyroid carcinoma is a rare malignancy accounting for approximately 1% of patients with primary hyperparathyroidism. Patients are typically symptomatic at presentation, often with the renal and skeletal, and rarely cardiac complications of severe hypercalcaemia.  There are no pathognomonic features of parathyroid carcinoma on histopathology.  A set of morphologic criteria and immunohistochemistry (such as Ki-67 and cyclin D1, and loss of parafibromin) may assist the diagnosis. Morbidity and mortality is secondary to intractable hypercalcaemia.