Is primary hyperparathyroidism associated with less aggressive histological subtypes and clinicopathological features of papillary thyroid carcinoma? A large single-center cohort study

Abstract

Objective: The coexistence of primary hyperparathyroidism (PHPT) and papillary thyroid carci-noma (PTC) has been increasingly recognized; however, its impact on tumor behavior and clinicopathological features remains unclear. To investigate the association be-tween PHPT and the clinicopathological characteristics of PTC in a large single-center cohort.

Materials and Methods: This retrospective study included patients who underwent parathyroidectomy for PHPT between 2019 and 2024. Patients with concomitant PTC were identified and compared with a separate cohort of patients with PTC without PHPT. Demographic, biochemical, and clinicopathological features, including tumor subtypes and adverse pathological characteristics, were analyzed.

Results: Among 190 patients with PTC, 91 (47.9%) had concomitant PHPT. Patients with PHPT were older and more frequently female. Tumor size was significantly smaller in patients with PHPT. Aggressive histological subtypes were significantly less frequent in the PHPT group (8.8% vs. 21.2%, p = 0.017). In addition, capsular invasion, lym-phovascular invasion, perineural invasion, and lymph node metastasis were observed less frequently in patients with PHPT. Radioactive iodine use was also significantly lower in this group.

In the PHPT cohort (n = 750), the presence of concomitant PTC was not associated with significant differences in preoperative calcium, phosphorus, PTH, or ALP levels. However, patients with PTC had lower preoperative magnesium levels and exhibited distinct postoperative biochemical profiles.

Conclusion: PHPT may be associated with non-aggressive subtypes and more favorable clinico-pathological features in PTC. However, these findings should be interpreted cautious-ly, as tumor size and other potential confounders may influence the observed associa-tions. PHPT alone should not be considered a determinant for treatment de-escalation, and clinical decision-making should remain guided by established risk-adapted strategies. These findings may provide additional insight into risk stratification in patients with coexisting PHPT and PTC.