Ectopic parathyroid adenoma: single-centre experience from India

Abstract

Background: The commonest cause of primary hyperparathyroidism (PHPT) is hyperfunctional parathyroid adenoma (PA) (94%), parathyroid hyperplasia (<6%) and rarely parathyroid carcinoma (<1%). Excision of PA is a definitive cure with a success rate of 95%. Less than 15% have one or more hyperfunctioning glands in an ectopic location. Methods: Between 2014 to 2017, seven of the 13 patients with PHPT, who had failed surgical and noninvasive localisation, were included in the study. Hybrid localisation technique positron emission tomography-Computed tomography (PET-CT) with tracer 11C-choline was used. Location of parathyroid adenoma was classified using Perrier classification, which uses, letters A-G to describe the exact location of the adenoma. A 50% drop in PTH levels as compared with pre-incision values was confirmed as a cure. Results: The biochemical and hormonal profile of the 7 (54%) patients with ectopic PA are (mean±SD) serum calcium (mg/dL), 25OH-D (ng/dL) and PTH (pg/mL) 11.36 ± 0.82; 22.82 ± 8.57; 205 ± 105 respectively. Three of the seven had renal stones. In all, seven patients of PA were localised using PET-CT using tracer 11C-choline. The profile of PA were two type-G (intrathyroidal), one type-C (posterior mediastinum), two type-F (superior mediastinum), one of type D (mid region of posterior surface of thyroid parenchyma at the junction of recurrent laryngeal nerve and the middle thyroid vein) and one type B. Conclusion: Ectopic PA is rare. In a biochemically and hormonally confirmed PHPT and in failed imaging localisation techniques/failed neck exploration one should look for ectopic PA. Newer hybrid techniques combined with newer tracer agents (PET-CT) will help in localization of PA. To the best of our knowledge this is the first report of series of ectopic PA from a single center from India.

Keywords

• ectopic parathyroid adenoma
• positron-emission tomography-computed tomography scan
• primary hyperparathyroidism