Preoperative Clinical Prediction of Parathyroid Carcinoma: Two Rare Case Presentations and a Review of Literature.

BACKGROUND Parathyroid carcinoma represents about 0.005% of all malignancies and accounts for less than 1% of primary hyperparathyroidism cases. Precise preoperative diagnosis of parathyroid carcinoma is challenging, and it is usually diagnosed postoperatively by histological examination. Early suspicion of parathyroid carcinoma can lead to a more extensive surgical approach to reduce the risk of carcinoma recurrence. CASE REPORT The first case involves a 58-year-old woman who presented with severe back pain. An incidental finding on cervical magnetic resonance imaging of a soft-tissue-density mass at the right para-tracheal zone. The large size and the noticeable mass effect pushing the trachea and esophagus to the left side suggested the need for further investigations to rule out malignancy. Initially, it was thought to be a thyroid nodule investigated by fine-needle aspiration that revealed follicular thyroid cancer. After a histopathological examination, it was determined to be a parathyroid carcinoma. The second case involved a 30-year-old woman with a lower-limb tingling sensation. The significantly enlarged mass seen during thyroid ultrasound warranted surgical excision and histopathological analysis to rule out malignancy. Excision of what was considered a parathyroid adenoma revealed a histopathological finding of carcinoma, prompting a hemithyroidectomy. Both patients had high calcium and parathyroid hormone levels preoperatively. CONCLUSIONS Preoperative high calcium, intact parathyroid hormone, creatinine, and alkaline phosphatase, in addition to the lymphocyte-to-monocyte ratio and tumor diameter, are suggested to be predictive of parathyroid carcinoma diagnosis and should be carefully analyzed in all patients presenting with primary hyperparathyroidism.