Supernumerary intravagal parathyroid hyperplasia.

A 46-YEAR-OLD WOMAN was referred to National Cheng-Kung University Hospital in January, 1997 with a diagnosis of renal hyperparathyroidism. She was uremic and had received hemodialysis for 10 years. She had bone pain and muscular weakness for 2 years and experienced 2 episodes of fractures during this period. There were no palpable neck masses, and the remainder of the physical examination showed no significant findings. Laboratory assessments revealed a serum calcium concentration of 11.1 mg/dL (normal range, 8.1-10.1 mg/dL), a serum phosphorus concentration of 6.3 mg/dL (normal range, 2.5-5.0 mg/dL), an alkaline phosphatase level of 813 U/L (normal range, 30110 U/L), and an intact parathyroid hormone level of 1242 pg/mL (normal range, 10-65 pg/mL). Roentgenograms of the skull showed a pepper-andsalt appearance of the cranial bone and roentgenograms of the hands showed subperiosteal resorption of phalangeal bones. Sonographic examination of the neck revealed 5 hypoechoic nodules, 2 on the right and 3 on the left side. During an operation, 4 hyperplastic parathyroid glands adjacent to the thyroid gland were identified. Subtotal parathyroidectomy and cervical thymectomy were performed, leaving a wellvascularized remnant of the left superior parathyroid gland of about 60 mg. Special attention was paid to the left lateral neck because 3 hypoechoic nodules were shown by preoperative sonography. Within the left carotid sheath, a fusiform swelling of the vagus nerve that initially was thought to be a neurogenic tumor was seen opposite the upper pole of the thyroid (Figure). The perineurium was split longitudinally and a 1.0 × 0.5–cm brownish mass was carefully enucleated from between the vagus fibers. Unexpectedly, on examination of frozen and permanent sections, the intravagal tissue was proved to be hyperplastic parathyroid. Postoperatively, the serum calcium level dropped immediately to below the normal range and was maintained in the normal range with supplements of oral calcium carbonate and 1,25dihydroxyvitamin D3.