Parathyroid Carcinoma Coincident With Neurofibromatosis Type 1

Neurofibromatosis type 1 is a genetic disorder resulting from a mutation in the NF1 gene, and is known to have an association with hyperparathyroidism that is caused by parathyroid adenoma in almost all cases. Parathyroid carcinoma in neurofibromatosis type 1 is extremely rare. Among the reports of neurofibromatosis type 1 with comorbid hyperparathyroidism have been a patient with coincident pheochromocytoma and medullary thyroid cancer, and a patient with a mutation of the RET gene, the causative gene of multiple endocrine neoplasia (MEN). These cases suggest an association between neurofibromatosis type 1 and multiple endocrine tumors, but the detailed mechanism is still unknown. Moreover, a mutation in the HRPT2 gene has been noted as a genetic cause of parathyroid carcinoma, but at presents no genetic link between neurofibromatosis type 1 and a mutation in the HRPT2 gene has been demonstrated, and the association between neurofibromatosis type 1 and parathyroid cancer remains unclear. We have reported an extremely rare case of neurofibromatosis type 1 with coincident hyperparathyroidism that is caused by parathyroid carcinoma.