The mediastinal parathyroid.

: Of 573 patients explored for primary hyperparathyroidism (PHP), parathyroid tissue was found in the mediastinum in 64 (11.2%). Age, sex, symptoms, gland mass, and pathologic diagnoses did not differ significantly from those of all PHP patients. Mean preoperative serum calcium values were higher for patients with mediastinal parathyroid tissue than for all patients with PHP, although median serum calcium values were similar in both groups. Mediastinal parathyroid glands numbered 68, of which 55 (81%) were enlarged, and 13 were normal size. One-third (36%) of patients with mediastinal parathyroid tissue underwent more than one exploration for PHP. However, 43 (63%) of 68 mediastinal glands were found on first exploration of the neck. Sternotomy was carried out in 21 (3.6%) of the 573 patients with PHP but showed mediastinal pathology in only 15 cases, being unsuccessful in 29 per cent. Of the six failed sternotomies, four patients were cured by simultaneous or subsequent neck exploration and resection, and two remain hypercalcemic. "Culprit" parathyroid glands are those typically enlarged and histologically abnormal glands that are credited with causing PHP in a given patient. Of 60 patients whose mediastinal glands were culprits, 48 (80%) were retrieved on initial or subsequent neck exploration. Localizing studies were used in all reoperative patients, and results are evaluated in detail. If neither CT scan nor angiogram localized the gland preoperatively, then sternotomy was always negative.