Supernumerary parathyroid glands: Frequency and surgical significance in treatment of renal hyperparathyroidism

Supernumerary parathyroid glands (SPGs) are found in 13% of random autopsie s. The high incidence of SPGs could explain the persistence or trigger recu rrence of renal hyperparathyroidism after surgery. The aim of this study wa s to assess the frequency and clinical relevance of SPG in patients-operate d on for renal hyperparathyroidism (HPT). In this retrospective study we re viewed the medical records of 290 patients with renal BPT who were initiall y treated in our department. We examined the anatomic and pathologic findin gs during cervical surgical explorat- ion and the outcome of HPT during fol low-up. SPGs were identified in 87 patients (30%) during the initial cervic otomy, corresponding to intrathymic parathyroid cell islets (one to four) i n 70 cases and to extrathymic SPG in 17 patients. Among 260 patients availa ble for follow-up, 11 experienced persistent HPT (4%), and 34 developed rec urrent HPT (13%). A total of 25 patients were reoperated on, and SPGs were responsible for 4 of 8 cases of persistent HPT and 4 of 17 cases of recurre nt HPT, representing an overall frequency of 32%. The anatomic distribution of SPGs found during reoperations included thymus, retroesophageal grove, carotid sheath, and mediastinum. SPGs are thus present in 30% of patients w ith renal HPT and are situated mainly in the thymus. Thymectomy. should be performed routinely during the first surgical exploration to prevent recurr ences arising from anterior mediastinal glands. SPGs were also responsible for 32% of persistent or recurrent HPT. In that setting, frankly ectopic SP Gs are not rare, and preoperative imaging appears highly desirable prior to embarking on surgical reexploration.