Prevalence, Diagnostic Imaging and Treatment Strategies of Intrathyroid Parathyroid Adenomas in Patients Surgically Treated for Hyperparathyroidism: A Review of the Literature

Abstract

Single parathyroid adenoma is the most common cause of primary hyperparathyroidism. Surgery is the definitive treatment. Intrathyroid parathyroid adenomas (ITPAs) can result in failure of the surgical procedure and persistence or recurrence of hyperparathyroidism. The aim of this review is to assess the prevalence of ITPAs, the efficacy of imaging studies in ITPA localisation as well as the efficacy of various surgical strategies. We conducted our search using the Medline database and searched for the keywords “intrathyroid parathyroid adenoma”. Eligibility criteria specified the availability of abstracts or full-text articles in English. Twenty five articles were considered relevant and were included in the synthesis of this article. The prevalence of ITPA in patients with primary hyperparathyroidism varies between 0.5% – 22.68%, with most studies reporting a frequency of 0.5% – 4.3%. The prevalence of ITPA in patients re-operated for persistent or recurrent hyperparathyroidism was 8.6% – 11%. The imaging modalities that are most commonly used are ultrasonography (US) and Technetium-99m sestamibi scintigraphy. A combination of both methods is associated with high diagnostic accuracy (81% – 92.3%). Thorough bilateral cervical exploration followed by thyroidotomy or thyroid lobectomy is the most common surgical strategy, although there are data that support low success rates. ITPAs are a rare cause of hyperparathyroidism that should not be neglected. Preoperative imaging is useful in the localisation of ITPAs. Bilateral cervical exploration followed by tumour enucleation or thyroid lobectomy is considered the best surgical strategy.