The Significance of Histologically “Large Normal” Parathyroid Glands in Primary Hyperparathyroidism

Abstract

Introduction We investigated outcomes in a cohort of patients with a biochemical diagnosis of primary hyperparathyroidism (pHPT) undergoing surgery for asymptomatic disease or target organ damage, where a focussed or four-gland operation was undertaken and the histopathology only reported a “large normal” parathyroid gland (LNP). Methods and materials Patients subjected to a parathyroidectomy for pHPT between 2012 and 2018 with a pathology of LNP were included. Patients with fat depletion or additional histological features of adenoma or hyperplasia in any of the resected glands were excluded. A control group was formed from 50 consecutive patients with the histological finding of adenoma or hyperplasia during the same study period. The primary outcome was biochemical normalisation of pHPT at 1–2\xa0weeks and after 6 months post-operatively. Results Forty-eight LNP patients (2% of all parathyroidectomies) were included in the study group with 50 matched controls. LNP patients had a lower biochemical cure rate (81% vs. 98% P \u2009<\u20090.05) and a higher risk of recurrence (10% vs. 0%, P \u2009=\u20090.06). LNP patients had a milder form of pHPT (Ca 2+ 2.63 vs. 2.68 P \u2009<\u20090.05) with a smaller PTH and Ca 2+ drop post-operatively. For LNP patients with failure, a definite additional cause of pHPT was found in only two patients. Conclusion This study highlights a controversial area in pHPT and reports LNP as a cause of pHPT. The biochemical analysis of this LNP group supports a benefit in resection in the setting of pHPT, although the risk of failure (persistence/recurrence) is higher than those with adenoma or hyperplasia. Stricter post-operative follow-up of LNP patients should be considered.