Giant mediastinal parathyroid adenoma, a rare cause of severe acute hyperparathyroidism
Salwan Maqdasy1,3, Françoise Desbiez3, Elena Robu2,3, Marie Batisse2,3, Beatrice Roche3, Jean Baptiste Chadeyras2,3 & Igor Tauveron2,3
Introduction: Ectopic parathyroid adenoma is a rare cause of primary hyperparathyroidism, it accounts for 10% of parathyroid adenomas.
Observation: A 56 years old man with no past medical history developed sudden acute renal failure after few weeks of fatigability, polydypsia and emesis. Hypercalcemia of 4.20 mmol/l (2.22.5 mmol/l), serum creatinine of 306 mmol/l, hypophospatemia 0.72 mmol/l (0.801.5 mmol/l) and high alkaline phosphatase 205 IU/l were the abnormalities detected on basic biochemistry. Parathyroid hormone assessment (PTH 1750 ng/ml (1565 ng/ml)) and high urinary calcium levels confirmed the diagnosis of primary hyperparathyroidism.
Hemodialysis, hydration and bisphosphonates were sufficient to normalize hypercalcemia and to improve his renal function.
I123-Tc99 Sesta MIBI scan with a hybrid camera demonstrated an intense hyper fixation of a mediastinal mass, confirmed when coupled with CT scan, to be necrotic, of 5.5 cm just in front of aortic arch.
Osteoporosis was confirmed on DXA absorbiometry with T score −3.4 DS on femoral head.
Via thoracoscopy, the tumour was removed completely and confirmed histologically. Per operative parathyroid hormone levels reduced with in 30 min to 150 ng/ml.
Multiple endocrine neoplasia genetic screening is proceeding, as he had severe hyper gastrenemia on hormonal analysis.
Conclusion: (1) Ectopic parathyroid tissue is rare but may be a cause of severe hyperparathyroidism of acute presentation.
(2) Sesta MIBI scan is important preoperative imaging in the evaluation of primary hyperparathyroidism to localize all active parathyroid tissues. Its role is magnified when coupled with a tomography via hybrid camera to describe and localize the tumour directly.
(3) Most ectopic parathyroid adenomas are of small size, yet Large mediastinal tumours might be mistakenly understood as paraneoplasic causes of hypercalcemia, but can easily be ruled out by intact parathyroid hormone sampling confirming the diagnosis of parathyroid adenoma.