Endocrine Abstracts

Introduction: Primary hyperparathyroidism is a common disease. It is generally caused by a solitary parathyroid adenoma. Adenomas weighing more than 3.5 g are classified as giant. These giant parathyroid adenomas constitute a rare clinical entity.

Patients and Methods: We report two cases of giant parathyroid adenoma observed in our department of otorhinolaryngology and cervicofacial surgery.

Results: Case 1: A 54-year-old woman was referred to our ENT department for the management of recent hypercalcaemia. She had no previous medical history. She complained of mild constipation, muscle weakness, nausea and intermittent abdominal pain for one month. Cervical examination did not find any palpable masses. Biologically, there was severe hypercalcaemia at 5.59 mmol/l and a PTH level of 2268 pg/ml. SPECT-CT revealed a right parathyroid adenoma measuring 6×2.7×2 cm in the anterior mediastinum with minimal cervical expression. The patient was managed urgently in the intensive care unit with hyperhydration, forced diuresis and bisphosphonates. The patient underwent double team surgery (cervicofacial surgery and vascular surgery). The parathyroid adenoma was successfully removed by a transcervical approach. Final pathology confirmed the diagnosis of a giant parathyroid adenoma. Post-operative management was straightforward. Her serum calcium and PTH levels normalized rapidly. The patient is currently asymptomatic and normocalcaemic.Case 2: The patient is 70 years old, diabetic, coronary and chronic renal failure(on haemodialysis since 2019). She had been suffering from diffuse bone pain for a year with functional impotence, especially in the two lower limbs. A parathyroid workup revealed a blood calcium level at the upper limit of normal and an elevated PTH level of 1160 pg/ml even after correction of hypovitaminosis D. Scintigraphy found two MIBI-binding sites, one of which is large and projects below the left lower pole. MRI and CT scan found a 4 cm calcified left basicervical mass extending into the upper mediastinum. The patient underwent a subtotal parathyroidectomy with removal of the subthyroidal lower laterotracheal mass. The postoperative follow up was straightforward. The PTH was back to 35 pg/ml on postoperative day 3 with a blood calcium level of 2.05 mmol/l. Pathological examination concluded to a giant parathyroid adenoma associated with hyperplasia of the remaining parathyroids. The evolution was marked by a regression of bone pain.

Conclusion: Giant parathyroid adenomas are usually solitary. Their treatment is surgical but would require medical preparation. The main post-operative complication is hypocalcaemia. Parathyroid carcinoma remains the main differential diagnosis and can only be ruled out by definitive pathological examination.