Surgical anatomy of hyperparathyroidism.

The number of glands and the exact location of each normal and pathological parathyroid identified in 416 parathyroidectomies for primary and secondary hyperparathyroidism have been recorded during the last 25 years (1966-1990). Nineteen per cent of all glands were found in ectopic locations. Half of these were distant from the thyroid lobes, most frequently posteriorly alongside the oesophagus, or in the upper anterior mediastinum encapsulated in the thymic remnant. Their discovery required, in some cases, extensive dissections, but a sternotomy was necessary in two cases only. Parathyroid glands may be concealed in the thyroid or in other aberrant locations, more rarely encountered. Supernumerary parathyroids were observed in 5% of cases. They were often pathological and were often in abnormal positions. A sound knowledge of the anatomic variations and of the paths of embryologic migration of the parathyroids are the essential clues for their detection.