Endocrine Abstracts

61-year-old-male with a background of treated hypertension and dyslipidaemia presented to accident and emergency with progressive shortness of breath. His most recent bloods were within normal limits. He has a positive family history of cardiac disease, and underwent investigation by CT scanning. This revealed a 10.2 mm anterior mediastinal nodule, which was not avid on PET CT scan. His case was reviewed by the respiratory team and he underwent a left VATs thymectomy. Thymic tissue was sent for histology revealing thymic hyperplasia with ectopic hyperplastic parathyroid tissue within the specimen. Post-surgery his biochemistry was normal. At endocrine follow up 4-months later he demonstrated a low/normal calcium of 2.20 mmol/l, phosphate 0.77 mmol/l, total vitamin D 77 nmol/l and PTH 6.7 pmol/l. There was no family history of parathyroid dysfunction or multiple endocrine neoplasia. His breathlessness improved and interestingly he remains asymptomatic of any endocrine imbalances. He remains under blood surveillance. Ectopic parathyroid glands have a prevalence of approximately 16%. The inferior parathyroid glands and thymus derive from the third embryological pouch. Their anatomical variability owes to abnormal migration during embryogenesis. The thymus is the most common site of ectopy. Most reported cases present with symptoms of hypercalcaemia, and are localised by PET scan. In this case, FDG-PET was used; assumedly due to its wider availability. Notably this modality has a reduced sensitivity and positive predictive value in detecting pathological parathyroid glands compared to 18F-FCH PET. At present, the function of the hyperplastic parathyroid gland is unknown. It also remains unclear as to whether resection of the asymptomatic parathyroid tissue will lead to abnormalities in bone biochemistry over time. This poses an important clinical consideration: despite normal biochemistry, should we be refining the way we evaluate the thymus pre-operatively? Long term follow up will provide more clarity.