Intracranial metastatic parathyroid carcinoma: case report.

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.