Objective and importance: Parathyroid carcinoma is a rare entity, and fewer than 200 cases have been described. It is a slowly progressive disease characterized by frequent recurrences and local metastases. Most patients with parathyroid carcinoma die from metabolic complications of hyperparathyroidism. Five-year survival rates range from 25 to 50%. Functional parathyroid carcinoma is a rare cause of hyperparathyroidism that affects only 0.32 to 5% of all patients who undergo surgery for hypercalcemia. A review of the literature revealed only one other reported case of metastatic intracranial parathyroid carcinoma, in a patient who experienced local recurrence and metastatic disease when she was diagnosed with an intracranial lesion.
Clinical presentation: We report the case of a 44-year-old African-American man with recent-onset, right lower-extremity weakness and hypercalcemia 4 years after he underwent a parathyroidectomy for parathyroid carcinoma. At presentation, his parathyroid level was 467 pg/ml, and his serum calcium level was 15.2 mg/dl. Imaging studies revealed an isolated enhancing left mesial frontoparietal mass. A systemic Cardiolite study demonstrated a single focus of radiotracer uptake in this region. No abnormal uptake was demonstrated in the neck or elsewhere.
Intervention: The patient underwent a frameless stereotactic interventional magnetic resonance imaging-guided resection via a parasagittal interhemispheric approach. Pathological findings were consistent with parathyroid carcinoma. After resection, his right lower-extremity weakness and secondary hyperparathyroidism resolved.
Conclusion: The typical natural history of parathyroid carcinoma concludes with death from complications of hyperparathyroidism. This case report supports aggressive surgical management to eliminate all parathyroid hormone-secreting malignant tissue and prevent metabolic complications. In this patient, intraoperative magnetic resonance imaging was helpful to ensure complete resection.