Intrathyroid adenomas in primary hyperparathyroidism: are they frequent enough to guide surgical strategy?

BACKGROUND: Ectopic parathyroid adenoma, including intrathyroid adenoma, is a common cause of failed parathyroid operations. The aim of this study was to evaluate the operative strategy/outcome in patients with primary hyperparathyroidism (pHPT), with special regard to intrathyroid adenomas.
METHOD: The authors performed an analysis of all patients receiving operative treatment for pHPT from 2003 through 2005. The operative strategy consisted of systematic perithyroid exploration followed by extended cervical exploration in cases where the adenoma was not found initially. In cases of persistent, high intraoperative parathyroid hormone levels, hemithyroidectomy was performed on the side with higher suspicion of intrathyroid adenoma or with more extended thyroid changes.
RESULTS: During the study, 115 patients received surgical treatment for sporadic pHPT. A single parathyroid adenoma (normal parathyroid position) was found in 95 patients (82.6%), ectopic single adenoma was found in 7 patients (6.1%), and double adenomas were found in 10 (8.7%) patients. Operative failure occurred in 3 cases (2.6%). In all, 4 of 7 ectopic single adenomas were intrathyroidal and were removed by hemithyroidectomy according to the authors' standard protocol.
CONCLUSION: The strategy of (a) cervical exploration, (b) extended cervical exploration, and (c) hemithyroidectomy was highly successful for removing undetectable intrathyroid parathyroid adenomas during primary intervention, thereby reducing the risks associated with reintervention.