A masquerading parathyroid carcinoma

E Casselden1, M Cherko1, R Gardy2, R Moorthy1 (1 ENT department, 2 histopathology department, Wexham Park Hospital, NHS Frimley Health Foundation Trust).

A 79-year-old man underwent routine biochemistry tests at the GP, showing hypercalcaemia of 2.77. Further testing confirmed primary hyperparathyroidism (PTH 14.4), and the patient was referred to the endocrinology team. The patient was worked up for parathyroidectomy, and ultrasound and fine needle aspiration cytology (FNAC) demonstrated a left inferior parathyroid adenoma, but also right-sided thyroid nodule which was U5, Thy4. A sestamibi scan showed an avid area in the left lower lobe of thyroid consistent with a probable parathyroid adenoma, but also highlighted the right-sided presumed thyroid nodule with high uptake. The patient underwent targeted left inferior parathyroidectomy and right hemithyroidectomy.

Interestingly, histology showed that the right sided mibi-avid nodule was in fact a parathyroid carcinoma rather than a thyroid nodule. The left inferior parathyroid adenoma was confirmed. Further to this there was an incidental micropapillary thyroid cancer (pT1a N0).

As far as we are aware, this is the first reported case of this trio of pathologies, discovered synchronously in one patient. It highlights the need for suspicion of mibi-avid, presumed thyroid nodules in the setting of hypercalcaemia, even when an ultrasound and FNAC are consistent in reporting thyroid pathology.