Shifting incidence of solitary adenomas in the era of minimally invasive parathyroidectomy. A multi-institutional study.

Background: Previously, when a conventional neck exploration (CNE) without preceding diagnostic imaging was the surgical treatment for patients with primary hyperparathyroidism (pHPT) solitary adenomas were observed in 69-88% of patients. The advent of minimally invasive parathyroidectomy (MIP), aiming at a preoperatively identified parathyroid abnormality may be associated with a different incidence of solitary and multiglandular parathyroid disease.

Materials And Methods: In a cohort of 467 patients with sporadic pHPT who preferentially underwent MIP in four hospitals in the same geographical region, the incidence of solitary adenomas, multiple adenomas, and multiglandular hyperplasia (MGD) was evaluated.

Results: A total of 367 patients were scheduled for MIP; 100 patients underwent a planned CNE. The overall surgical success rate of the first operation was 93%, and the cumulative success rate, including a second operative procedure, was 99%. Normocalcemia resulted from removing 1 abnormal PG in 426 patients (91%) and more than one abnormal gland in 35 patients (8%). A parathyroid carcinoma was diagnosed in four of the 426 patients with a single abnormal gland. Four gland hyperplasia was observed in 1 patient. In hospitals where diagnostic workup usually consisted of ultrasound (US) and computed tomography (CT) the incidence of solitary adenomas was 88%, compared with 96% in hospitals where MIBI, US, and CT were used preoperatively (P = 0.007).

Conclusions: A higher frequency of solitary adenomas was observed than historically reported. The extent of the preoperative workup influences the number of observed solitary adenomas.