Imaging localization and surgical approach in the management of ectopic parathyroid adenomas

Abstract

Objective: (1) Review the anatomy and epidemiology of ectopic parathyroid adenomas (EPAs), (2) summarize the role of relevant imaging modalities in the localization of EPAs, and (3) characterize surgical approaches for various ectopic locations. Methods: Literature review of published English-language articles from 1995 through August 2017. Results: Summary of the literature indicates that the prevalence of EPA is approximately 20% in unexplored patients with primary hyperparathyroidism, but it is as high as 66% in re-operative patients. EPAs may be located anywhere from the carotid bifurcation to the aortopulmonary window. Ultrasound has limited accuracy in identifying EPAs except near the thyroid and thyrothymic ligament and requires expert experience from the user. Among dual-phase 99mTc sestamibi scintigraphy techniques, hybrid imaging with both single-photon emission computed tomography (SPECT) and computed tomography (CT) (SPECT/CT) is superior to planar scintigraphy or SPECT alone at localizing EPAs. Four-dimensional computed tomography (4DCT) precisely delineates important anatomic relationships and is highly sensitive in localizing EPAs. Although 4DCT requires radiation, intravenous iodinated contrast, and reader experience, it is well-equipped to detect lesions at various ectopic sites and guide the surgical approach. EPAs frequently require alternative surgical approaches. Re-operative parathyroidectomy may be attempted in patients having previously undergone bilateral neck exploration by an experienced surgeon once the lesion is colocalized by 2 repeat imaging modalities. Removal of nonlocalized disease requires a careful and systematic exploration of superior and inferior gland locations. Conclusion: EPAs pose challenges during both localization and surgical removal. High-volume experience and multidisciplinary care are necessary for optimal outcomes.