Abdel-Aziz TE, Parameswaran R, Gleeson F, Sadler G and Mihai R
Objective: This study compares the outcome of parathyroidectomy for primary hyperparathyroidism (PHPT) in patients whose adenomas’ weights were at the extremes of the distribution curve. As the size of parathyroid adenomas influences the success rate of localization studies for PHPT and negative localization can lead to higher risk of failed surgical treatment, it is possible that a difference in cure rate could be observed between subgroups of patients.
Study design: Case series.
Methods: Data were retrieved from a prospective database maintained in a large University hospital.
Results: From a cohort of 519 patients who underwent parathyroidectomy for PHPT; two subgroups of patients were identified based on the extreme 10% of the distribution curve for adenomas’ weight: adenomas <300 mg (“dwarfs”, n=100, median 200 mg) and >3000 mg (“giants”, n=56, median 4300 mg). Age was similar between groups. In comparison with giant adenomas, dwarf adenomas were associated with less severe hypercalcaemia (median 2.84 vs. 3.00 mmol/l, p<0.001) and lower PTH (median 11.7 vs. 25.6 pmol/l, p<0.001). The occurrence of dwarf adenomas showed no trend during the study period (23/173 (13%) in 2000-2004 vs. 36/217 (17%) in 2007-2011).
Scan-directed parathyroidectomy was feasible in significantly more patients with giant adenomas (59% vs. 38%). Persistent disease was diagnosed in three patients with dwarf adenomas and all were cured after a second operation. Patients with giant adenomas had no recurrence during a median follow-up of 25 months even though eight patients had histological features suggestive of atypical/malignant tumors.
Conclusion: Preoperative biochemistry is a poor predictor of adenomas’ size even at the extremes of the distribution curve. Cure can be achieved in all patients with “dwarf” adenomas. Even in the presence of suspicious histological features, “giant” adenomas did not show malignant behavior.