Endocrine Abstracts

JOINT1437

Introduction: Persistent hyperparathyroidism (PHPT) poses diagnostic and therapeutic challenges, particularly when coexisting with severe comorbidities. This case illustrates how PHPT influenced the treatment course of bilateral oncocytic adrenocortical carcinoma (ACC), underscoring the need for multidisciplinary management in addressing such complexities.

Case Description: A 60-year-old woman was diagnosed with oncocytic ACC in 2021, requiring left nephrectomy and adrenalectomy. Histopathological analysis confirmed oncocytic ACC with significant malignant potential (Ki67 18.5%, Weiss score 6). Despite initial surgical success with no evident metastases, severe hypercalcemia (>3 mmol/l) and renal impairment (eGFR 30–40 mL/min) revealed concurrent PHPT. Subtotal parathyroidectomy confirmed four-gland hyperplasia, yet hypercalcemia persisted postoperatively, delaying planned adjuvant mitotane therapy. In 2023; ¹⁸F-Fluorocholine PET/CT localized an ectopic parathyroid adenoma at the sternocostal junction. A second surgery in May 2023, involving VATS exploration of the mediastinum and thymectomy, failed to locate the adenoma. A third surgery in October 2023, performed via sternotomy, successfully removed the ectopic adenoma, confirmed histopathologically. Intraoperative PTH monitoring demonstrated a significant decrease, indicating surgical success. During this period, a second ACC lesion was identified on the contralateral adrenal gland. In 2024, the patient underwent right adrenalectomy, with histopathology confirming an oncocytic ACC (Weiss score 4, Ki67 9%). Importantly, neither the initial nor the subsequent ACC exhibited functional activity at any postoperative stage. While it remains unclear whether the lesion represents a metachronous or metastatic process, delayed adjuvant therapy after the initial diagnosis likely influenced the clinical course. Postoperatively, hypoparathyroidism required intensive calcium and vitamin D supplementation. Subsequent DXA scans demonstrated improved bone mineral density, while renal function remained compromised due to solitary kidney calculosis and CKD (eGFR ~28–33 mL/min). Management of this case required close collaboration between endocrinologists, surgeons, nephrologists, and oncologists to address the overlapping challenges of PHPT and bilateral ACC. Multidisciplinary planning was crucial for integrating diagnostic imaging, surgical interventions, and long-term metabolic and oncologic care.

Conclusions: This case highlights the bidirectional impact of PHPT and ACC management, demonstrating how endocrine dysfunction may alter oncologic treatment strategies and outcomes. Advanced imaging modalities, repeated surgical interventions, and close interdisciplinary collaboration are crucial in addressing such complex cases.