Giant parathyroid adenoma and challenges with preoperative differentiation from malignancy

Giant parathyroid adenomas are rare and underreported benign tumours of parathyroid gland. Preoperative differentiation between giant parathyroid adenoma (GPA) and parathyroid carcinoma can be challenging, as they both may present as a large parathyroid tumour with hyperparathyroidism. Very few GPAs had been described in the literature, with only 60 cases including our present case. We report a case of GPA and the preoperative diagnostic challenges we faced in differential diagnosis of a potential parathyroid malignancy. As a parathyroid malignancy could not be excluded preoperatively the parathyroid tumour was excised en bloc with surrounding thyroid lobe. The histology was contributory to exclude parathyroid malignancy confirming a benign GPA.