Primary Hyperparathyroidism with Thyroid Cancer: Clinicopathologic Features.

[OBJECTIVES] Concomitant thyroid disease affects almost half of the primary hyperparathyroidism (PHPT) patients. Pre-operative evaluation of the thyroid gland for the early diagnosis of thyroid carcinoma is essential in PHPT patients. Herein, we aim to investigate the clinicopathologic features that affect the type and extent of surgery in patients having PHPT and concomitant thyroid disease but especially thyroid cancer.

[METHODS] The files of consecutive patients who underwent parathyroidectomy for PHPT during a 6-year period were retrospectively reviewed. The cases who underwent parathyroidectomy and simultaneous thyroidectomy were enrolled in the study. A total of 84 patients who met the study criteria were divided into two groups as benign thyroid disease (Group 1) and malignant thyroid disease (Group 2) according to the final histopathological examination. The demographic and clinicopathological characteristics were compared between groups.

[RESULTS] Concomitant thyroid disease was found in 158 (55.6%) of 284 patients who were operated on for PHPT. Simultaneous total thyroidectomy or lobectomy was performed for 84 (29.6%) patients and thyroid carcinoma was detected in 29 (10.2%) patients. Total thyroidectomy and complication rates were higher in Group 2 (p<0.05). Pre-operative fine-needle aspiration biopsy was obtained in 58.3% of patients and it identified only 26.3% of histopathologically confirmed thyroid carcinoma. Only pre-operative serum phosphorus level was found higher in Group 1 (p<0.05), but none of the study parameters was found as an independent risk factor for thyroid malignancy (p>0.05) in multivariate analysis.

[CONCLUSION] There is no accepted parameter yet to predict the accompanying thyroid carcinoma in PHPT patients. However, a benign biopsy cannot exclude thyroid malignancy in PHPT patients and may cause undiagnosed thyroid carcinoma due to papillary microcarcinoma.