Endocrine Abstracts

A 67-year-old lady with no significant past medical history presented with a left-sided neck swelling. An FNA under ultrasound scan guidance revealed malignant cells of indeterminate origin. Left neck exploration revealed an enlarged left lobe of thyroid and a retrosternal mass extending into the aortic arch. A left thyroid lobectomy and removal of retrosternal mass was performed and the histology showed a thyroid colloid goitre and low grade paraganglioma respectively. She was normocalcaemic at this time (2.37 mmol/l; NR 2.10–2.60). Three years later she presented a recurrent left-sided neck lump. Given the previous history the lesion was excised and histology revealed a recurrent paraganglioma. Excision was felt to be incomplete at surgery and she was referred for radiotherapy. Post-operatively she was hypercalcaemic (3.35 mmol/l) with raised PTH levels (16 pmol/; NR 1.1–6.9). Because no parathyroid adenoma was identified during previous surgery ectopic PTH secretion by the paraganglioma was considered as a cause of the hypercalcaemia. In situ hybridisation confirmed the presence of PTH mRNA within the paraganglioma tissue. She remained persistently hypercalcaemic suggesting residual disease and repeat exploration of the right neck led to removal of further paraganglioma tissue. She remained hypercalcaemic (range 2.65–3.5 mmol/l) and generally well, although at times of intercurrent illness required admission with acute pancreatitis. Currently she is asymptomatic with stage 3 CKD and her current calcium is 2.65 mmol/l with no recent episodes of pancreatitis.

Elevated calcium in the context of a raised PTH usually suggests a parathyroid adenoma. Differential diagnoses include familial hypocalciuric hypercalcaemia and parathyroid hyperplasia associated with multiple endocrine neoplasia. In this case ectopic PTH secretion by a paraganglioma was diagnosed. There are few similar case reports in the literature. Because of this lady’s previous invasive surgery, it was felt that a fourth operation was inappropriate given her relative lack of symptoms. The question of a potential role for calcimimetic agents is raised by this case.