Diagnostic localization of ectopic parathyroid lesions: developmental consideration

Parathyroid glands arise from the third and fourth pharyngeal pouches. Parathyroid lesions sometimes develop ectopically. The aim of this article is to illustrate the knowledge of pharyngeal apparatus development to assist with diagnostic localization of ectopic parathyroid lesions. We retrospectively reviewed charts of 23 patients who received a diagnosis of ectopic parathyroid lesions. The ectopic lesions were widely distributed; cranially lesions were located on the carotid bifurcation, caudally in the right paraaortic region, ventrally on the surface of the sternohyoid muscle, and dorsally in the paraesophageal region. In most cases, parathyroid tissues were associated with structures related to the third or fourth pharyngeal pouches that traveled to regions where the ectopic lesions ultimately developed. In a few cases, lesions were not associated with these pouches and might have developed from parathyroid tissue that migrated due to an anomalous pathway of parathyroid travel. When patients present without entopic lesions, the presence of ectopic lesions should be evaluated based on an understanding of the developmental mechanisms of parathyroid glands and the frequency with which ectopic lesions have been found in specific locations. Systematic diagnosis can minimize the frequency with which ectopic lesions are missed during clinical care and maximize their accurate localization.