SURGICAL SIGNIFICANCE OF SUPERNUMERARY PARATHYROID-GLANDS IN RENAL HYPERPARATHYROIDISM

In secondary hyperparathyroidism (2HPT) fundamentally all parathyroid glands, including supernumerary glands, become hyperplastic, and stimu lation of parathyroid glands continues after parathyroidectomy (PTx). Therefore supernumerary glands have special significance during surger y for 2HPT, whether persistent or recurrent HPT. In the present study 570 patients underwent initial total PTx with a forearm autograft. The frequency, type, location, histopathology, and clinical significance of the supernumerary glands were evaluated. At the initial operation 9 0 supernumerary glands were removed from 82 of 570 patients (14.4%); 1 2 patients (2.1%) required extirpation of supernumerary glands for per sistent/recurrent HPT. Altogether 104 supernumerary glands were identi fied at operation in 94 of the 570 patients (16.5%). Among these 104 g lands, 25 (24.0%) were of the rudimentary, or split, type and 79 (76.0 %) of the proper type. Supernumerary glands were most frequently ident ified in the thymic tongue (53/104, 51.0%); 32 (60.4%) of these 53 gla nds were identified only microscopically. In 6 of the 570 cases (1.1%) , reoperation was required for persistent HPT due to supernumerary gla nds located in the mediastinum, and 6 patients underwent neck reexplor ation for recurrence. Histopathologically, 61 of 104 (58.7%) supernume rary glands, including 36 glands recognized only microscopically, show ed diffuse hyperplasia, and 43 (41.3%) displayed nodular hyperplasia. Residual small supernumerary glands with diffuse hyperplasia have the potential to be transformed to nodular hyperplasia during long-term he modialysis. Therefore all parathyroid glands including supernumerary g lands should, if possible, be removed at the initial operation. Routin e removal of the thymic tongue and careful examination of the regions surrounding the lower poles of the thyroid, especially on the left sid e, are important steps in the surgical treatment.