Development of primary hyperparathyroidism after cardiothoracic surgery: a case of ectopic mediastinal parathyroid adenoma
R Ali1, S Jarvis1, M Siddiqui1, F Palazzo2, G Madani1, V Bravis1 ,1Imperial College Healthcare NHS Trust, St Mary’s Hospital, Paddington, London W2 1NY, 2 Imperial College Healthcare NHS Trust, Hammersmith Hospital, London W12 0NN
Case: A 54-year-old male was referred to endocrinology services after developing hypercalcaemia following coronary artery bypass graft (CABG) 5 months earlier. Post procedure bloods revealed a rapid increase in calcium (corrected) from 2.17mmol/L (Day 1 post-surgery) rising to 2.63mmol/L within 5 days with a raised PTH of 11.1 pmol/L consistent with primary hyperparathyroidism. He remained asymptomatic with no end-organ damage (no nephrocalcinosis or osteoporosis). Ultrasound of the parathyroid glands did not reveal an adenoma. Sestamibi SPECT-CT revealed a 6mm ectopic parathyroid in the anterior mediastinum. After Endocrine multidisciplinary discussion, he will undergo thoracoscopic procedure for a likely ectopic mediastinal parathyroid adenoma.
Discussion: Ectopic mediastinal parathyroid adenomas (MPAs) are relatively uncommon causes of primary hyperparathyroidism. Due to the common third arch origin of the inferior parathyroid gland with the thymus, they have a more extensive embryological migration pattern. Thus, inferior parathyroid glands are more frequently ectopic than superior glands and mostly found within or near the thymus gland.
Definitive management may be challenging since MPAs are not accessible by cervical incision, and removal may require a sternotomy or minimally invasive video-assisted thoracoscopic surgery (VATS). There are few reported cases of ectopic MPA removal in previous CABG but with risk of gland division, and increased chance of encountering scar tissue and adhesions. Accurate imaging to localise the glands is essential.
There are no official recommendations in existing guidelines for ectopic parathyroid adenomas. MDT debate includes the option of conservative management and surgery due to the risk/benefit analysis. The patient in our case has a long-life expectancy and is likely therefore to benefit from surgery.