Giant parathyroid adenoma presenting with severe hypercalcemia mimicking parathyroid carcinoma in a patient with chronic kidney disease: a case report.

Giant parathyroid adenomas (GPAs) are rare lesions that may clinically and radiologically mimic parathyroid carcinoma, particularly when associated with severe hypercalcemia. A 63-year-old male with hypertension and chronic kidney disease presented with symptomatic hypercalcemia and severe hyperparathyroidism. Laboratory evaluation revealed markedly elevated serum calcium and parathyroid hormone levels. Imaging demonstrated a large left-sided parathyroid mass suspicious for adenoma versus carcinoma. Following multidisciplinary evaluation, the patient underwent en bloc resection consisting of left thyroid lobectomy, parathyroidectomy, and central lymph node dissection. Intraoperative parathyroid hormone monitoring demonstrated a decline of more than 50%, confirming adequate excision according to the Miami criterion. Histopathological examination showed a GPA with cystic changes and no evidence of malignancy. This case highlights the diagnostic challenge of differentiating GPA from parathyroid carcinoma and emphasizes the importance of histopathological confirmation and appropriate surgical planning.