Dwarfs and Giants of Parathyroid Adenomas—No Difference in Outcome After Parathyroidectomy

Backgroud: 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, it is possible that a difference in cure rate could be observed between subgroups of patients. Materials and 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). In comparison with giant adenomas, dwarf adenomas were associated with less severe hypercalcemia (median 2.84 versus 3.00 mmol/L, P < 0.001) and lower PTH (median 11.7 versus 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 versus 36/217 [17%] in 2007-2011). Scan-directed parathyroidectomy was feasible in more patients with giant adenomas (59% versus 38%). Persistent disease was diagnosed in three patients with dwarf adenomas. Patients with giant adenomas had no recurrence during a follow-up of 40 mo even though eight patients had histological features suggestive of atypical/malignant tumors. Conclusions: 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.