MEN1 and parathyroid gland carcinoma: However, allocation of the involved parathyroid glands in MEN1 requires special consideration: Multiple parathyroid gland hyperplasia is common, with higher rates of ectopic gland location and parathyroid carcinoma compared with PHPT in the general population [32, 34, 35], with 20% chance of ectopic gland location in patients with MEN1 requiring reoperation for recurrent PHPT [36].