[Supernumerary ectopic hyperfunctioning parathyroid gland: a potential pitfall in surgery for sporadic primary hyperthyroidism]

STUDY AIM: The aim of this retrospective study was to report a series of nine patients with a sporadic primary hyperparathyroidism, operated on for an ectopic supernumerary hyperfunctioning parathyroid gland. PATIENTS AND METHOD: From 1973 to 1998, among a total of 1,307 patients operated on for a primary hyperparathyroidism, 9 (0.69%) had an ectopic supernumerary hyperfunctioning gland. There were six women and three men (mean age: 63 years) with a sporadic hyperparathyroidism. Initial cervicotomy was performed in our institution in 6 cases. The nine patients underwent 19 operations including one through sternotomy. The ectopic parathyroid gland was localized in the eight patients who had preoperative localization studies. RESULTS: The supernumerary gland was located in the anterior mediastinum (n = 6), in the carotid sheath (n = 2) and within the vagus nerve (n = 1). In three patients, it was found during the initial cervicotomy. In the 6 other patients, it was found in the course of a reoperation. With a mean follow-up of five years, all the patients were biochemically cured. One patient had a permanent recurrent nerve palsy and a definitive hypoparathyroidism. CONCLUSIONS: The low incidence of an ectopic supernumerary hyperfunctioning parathyroid gland in sporadic hyperparathyroidism does not justify the routine use of preoperative localization studies and intra-operative quick parathormon assay. During an initial conventional cervicotomy the search for a 5th gland is highly recommended when 4 normal glands have been found in the neck. This research should also be performed in case of multi-glandular disease.