A Case of Primary Hyperparathyroidism with Concomitant Papillary Thyroid Carcinoma

Primary hyperparathyroidism (PHPT) with concomitant thyroid cancer is rare and is usually caused by a parathyroid adenoma rather than parathyroid carcinoma. Although an association between PHPT and well-differentiated thyroid carcinoma has been reported, it is often considered coincidental. We report a case of a 50-year-old female presenting with tingling, shoulder pain, muscle weakness, and elevated serum calcium and parathyroid hormone levels. Neck ultrasonography revealed a hypoechoic nodule in the left inferior region to the thyroid gland and thyroid nodules in both lobes. A Tc99m-MIBI parathyroid scan showed a focal hot nodule, and fine-needle aspiration confirmed papillary thyroid carcinoma, later verified by histopathology. The patient underwent surgery and was diagnosed with PHPT and papillary thyroid carcinoma. This case highlights the importance of evaluation for concomitant thyroid malignancy in PHPT patients with suspicious thyroid nodules.