A Case of Intrathyroid Parathyroid Adenoma in a Postmenopausal Woman with Primary Biliary Cholangitis

Abstract

An 80-year-old woman with a 12-year history of primary biliary cholangitis (PBC) was referred to our hospital due to chronic hypercalcemia and urolithiasis. Her serum calcium levels had remained between 10.8 and 11.0 mg/dl for the past year. Bone mineral density testing revealed that the lumbar spine was at 64% of the young adult mean. These findings led to a suspicion of primary hyperparathyroidism (PHPT). Neck ultrasonography and contrast-enhanced CT scans identified two lesions within the right thyroid : one on the dorsal aspect and another at the lower pole of the lobe. Following bilateral neck exploration, a right hemithyroidectomy was performed to remove the two tumors. Histopathological examination revealed that the lesion on the dorsal side was a thyroid follicular adenoma, while the one partly within the lower pole was a parathyroid adenoma. Parathyroidectomy is the recommended management for patients with PHPT and PBC who are at high risk of fractures due to osteoporosis caused by these conditions. This case underscores the importance of surgical intervention even when preoperative imaging fails to clearly identify parathyroid lesions.