[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.