Recurrent secondary hyperparathyroidism due to a gradually increasing intrathyroidal parathyroid adenoma in a fifth parathyroid gland of a patient undergoing long-term haemodialysis: Road to evil.

backgroundAn intrathyroidal parathyroid adenoma (IPA) is a very rare cause of recurrent hyperparathyroidism after parathyroidectomy in patients undergoing long-term haemodialysis. An IPA is often difficult to localize preoperatively, making diagnosis and treatment challenging. We herein report a rare case of recurrent hyperparathyroidism due to a gradually increasing IPA in a fifth parathyroid gland. CASE PRESENTATION: A 24-year-old Chinese woman had end-stage renal disease secondary to chronic glomerulonephritis and started regular haemodialysis in March 2007. She was diagnosed with renal hyperparathyroidism as indicated by elevated parathyroid hormone and calcium levels in 2011. One year later, the parathyroidectomy with right forearm autotransplantation was performed in January 2012. Pathology revealed parathyroid nodular hyperplasia in four of the nodules. Twelve years after surgery, the nodule in the right thyroid was detected by multiple imaging modalities. In addition to the recurrence of renal hyperparathyroidism, the nodule gradually increased in size. Total right thyroid lobectomy was performed, and the patient was diagnosed with an IPA. At the 3-month follow-up examination, she had no signs of recurrence despite regular haemodialysis, and her PTH and serum calcium levels were stable.

conclusionsThis is a rare case of recurrent hyperparathyroidism due to a gradually increasing fifth parathyroid gland in a patient who underwent long-term haemodialysis after parathyroidectomy. We suggest vigilant postoperative monitoring for prompt and early identification of culprit parathyroid lesions, even if the four parathyroid glands have been dissected.