Concomitant parathyroid hormone-secreting oncocytic adrenocortical carcinoma and parathyroid adenoma

A 53-year-old man underwent resection of a nonfunctional 9 cm oncocytic adrenal cortical carcinoma (ACC) with focal high-grade features. Two years later he presented again, with gynecomastia and elevated levels of estradiol, 11-deoxycortisol, and serum calcium (10.5 mg/dL, SI: 2.62 mmol/L) (reference range 8.4-10.2 mg/dL [SI: 2.10-2.55 mmol/L]). Imaging demonstrated locally recurrent ACC, which was resected. Steroid excess resolved and he started mitotane. Months after, his calcium was 11.9 mg/dL (SI: 2.97 mmol/L), parathyroid hormone (PTH) 209 pg/mL (SI: 22.0 pmol/L) (reference range 15-65 pg/mL [SI: 1.6-6.9 pmol/L]), and parathyroid hormone-related peptide (PTHrp) was undetectable. Germline genetic testing (TP53, MSH2, MSH6, MLH1, PMS2, and MEN1) was negative; localizing imaging demonstrated possible right inferior parathyroid adenoma. He underwent 4-gland parathyroid exploration. Right inferior parathyroid (460 mg) was excised, superior parathyroids appeared normal, and left inferior parathyroid was not identified. Intraoperative parathyroid hormone (IOPTH) did not drop appropriately. Follow-up calcium rose to 13.1 mg/dL (SI: 3.27 mmol/L) and PTH to 336 pg/mL (SI: 35.6 pmol/L). Repeat imaging demonstrated ACC recurrence. After cytoreductive surgery (nephrectomy and omentectomy) and heated intraperitoneal chemotherapy (HIPEC), calcium and PTH normalized. Staining of the recurrent ACC demonstrated PTH positivity. This is a novel case of PTH-secreting ACC and concomitant parathyroid adenoma.