Remote Recurrent Primary Hyperparathyroidism in Auto-Transplanted Tissue.

Multiple endocrine neoplasia type 2A (MEN2A) is a rare hereditary condition characterized by medullary thyroid cancer, pheochromocytoma, and primary hyperparathyroidism. The current standard of treatment of hyperparathyroidism involves surgical removal of visibly enlarged glands, and auto-transplantation of remnant tissue is often considered to minimize the risk of iatrogenic post-surgical hypocalcemia if multiple glands are enlarged. Rarely, hyperparathyroidism may recur due to hyperplasia or adenoma formation in the auto-transplanted tissue. The following case portrays a 51-year-old male, with a history of MEN2A status post total parathyroidectomy with cryopreservation and subsequent auto-transplantation of remnant parathyroid tissue to the left arm 18 years prior, who presented to establish care due to the insidious development of asymptomatic hypercalcemia. Workup included a laboratory examination showing elevated intact parathyroid hormone (PTH) and left arm ultrasound revealing three areas of enlarged parathyroid tissue at the transplant site, raising suspicion for the development of recurrent primary hyperparathyroidism in auto-transplanted tissue. The patient ultimately underwent a re-do subtotal parathyroidectomy of auto-transplanted tissue with surgical pathology confirming hyperplastic parathyroid tissue. This case highlights the significance of indefinite vigilant surveillance in this patient population, as a recurrence of hyperparathyroidism may occur even after decades of remission.