Metachronous double parathyroid adenomas involving two different cell types: Chief cell and oxyphil cell

Objective: To describe a patient with the rare occurrence of metachronous double parathyroid adenomas involving two different cell types. Methods: We present a case report and a summary of the related literature. Results: Double parathyroid adenomas are rare, occurring in 1.7 to 9% of patients with primary hyperparathyroidism. Most double parathyroid adenomas are synchronous lesions; few metachronous double parathyroid adenomas have previously been reported. Most parathyroid adenomas are of the chief cell variety, with oxyphil cell adenomas occurring in less than 1% of cases. In a 73-year-old man with no prior history or known family history of endocrine disease, primary hyperparathyroidism developed, and cervical ultrasonography demonstrated a mass in the right side of the neck. Subsequent parathyroidectomy revealed a right superior chief cell adenoma. Postoperatively, the patient's parathyroid hormone and serum calcium levels returned to normal and remained so for at least 9 years. Twelve years after the first operation, recurrent hyperparathyroidism prompted repeated surgical exploration of the neck, which disclosed a large left superior parathyroid mass. Surgical excision and histologic examination revealed the lesion to be an oxyphil cell adenoma. Conclusion: To our knowledge, this is the first reported case of metachronous double parathyroid adenomas involving two different cell types: chief cell and oxyphil cell.