Parathyroid glands: variation in number, size and location

Parathyroid glands PTGs develop from the pharyngeal pouches Their anatomy exhibits variations regarding their number and locations Parathyroid surgery is mostly gratifying in experienced hands but sometimes failing due to the possibility of ectopic positions of the glands Abnormal descent of the PTGs during development is responsible for these ectopic positions Supernumerary PTGs are usually diseased and ectopic inside the thyroid gland inside the thymus gland or elsewhere in the mediastinum In parathyroidectomies for primary and secondary hyperparathyroidism preoperative techniques for accurate localization of the PTGs are recommended like ultrasonography computed tomography CT magnetic resonance imaging MRI four dimensional computerized tomography DCT aminolevulinic acid induced fluorescence Technetium Tc m sestamibi scanning MIBI Tc m RBC imaging arteriography and selective venous sampling for parathormone For a successful parathyroidectomy a surgeon must be excellently aware of the anatomical variations development and pathophysiology of the PTGs