Endocrine Abstracts

JOINT2289

Introduction: Primary hyperparathyroidism (PHPT) is a frequently encountered endocrine disorder characterized by dysregulated parathyroid hormone (PTH) secretion, most commonly due to a parathyroid adenoma. The coexistence of PHPT and papillary thyroid carcinoma (PTC) is rare, with an estimated prevalence of 2.3–4.3%. This report presents a case of incidentally discovered PTC during the evaluation of PHPT.

Case Presentation: A 47-year-old female was admitted for the management of PHPT, initially detected during the investigation of persistent lumbosciatalgia. Laboratory findings revealed hypercalcemia (2.89 mmol/l) and significantly elevated PTH levels (1087 pg/mL). Morphological assessment included cervical ultrasound, which identified a 45 mm hypoechoic nodule in the retro-inferior thyroid region, highly suggestive of a parathyroid adenoma, along with bilateral thyroid nodules classified as EU-TIRADS 3. Cervical computed tomography (CT) confirmed a retrothyroidal tissue mass on the left side, with enhancement kinetics consistent with a parathyroid adenoma. SPECT-CT further supported the diagnosis by demonstrating an MIBI-avid tissue mass in the lower left pole, indicative of parathyroid origin. The patient underwent a left inferior parathyroidectomy and left thyroid lobectomy. Intraoperative frozen section analysis confirmed parathyroid tissue and unexpectedly revealed a papillary thyroid carcinoma, necessitating completion thyroidectomy. The final histopathological examination identified an encapsulated papillary thyroid carcinoma in the left lobe measuring 1.4 cm, with lymph node involvement (1N+/N), classifying the tumor as pT1aN1aMx. Consequently, the patient was referred to the nuclear medicine department for adjuvant radioactive iodine therapy.

Discussion/Conclusion: The concurrent occurrence of PHPT and PTC remains an uncommon finding, with its underlying pathophysiology not yet fully elucidated. Several hypotheses suggest a potential link, including shared embryological origins and common genetic mutations. This dual pathology poses significant diagnostic and therapeutic challenges, particularly when thyroid cancer remains unrecognized preoperatively. A meticulous preoperative evaluation, including intraoperative frozen section analysis, is crucial to prevent the need for reoperation and to optimize patient outcomes.

Disclosure of Interest: None declared