HISTORICAL CONSIDERATIONS The parathyroid glands, which are derived from the third and fourth branchial clefts,1 were first recognized and named by Sandström in 1880. A parathyroid tumor was first recognized by de Santi in 1900. Gradually the relation between such a tumor and the syndrome of von Recklinghausen's disease was realized, and in 1925 Mandl2 reported the cure of the latter by removal of an enlarged parathyroid gland. Since then, reports of about 200 cases have been added to the medical literature. ANATOMY The parathyroid glands are present in all animals down to fishes. They may be situated on, in or behind the thyroid gland but are most frequently found on its posterior aspect, near the point at which the inferior thyroid artery enters the gland.3 Rarely, aberrant or accessory parathyroid glands have been reported as present in the thymus or in the anterior mediastinum.4 Millzner