Endocrine Abstracts

JOINT499

Background: Thyroid paragangliomas (PGL) are rare neuroendocrine tumors, with nearly 75 cases reported globally. Arising from extra-adrenal paraganglia of the autonomic nervous system, they often present as slow-growing solitary thyroid nodules. While generally indolent and treatable through surgical excision, their malignant potential remains uncertain, necessitating long-term follow-up. Succinate Dehydrogenase Complex Subunit B (SDHB)-related thyroid PGL are exceptionally uncommon, with limited literature and no established guidelines for their management. The SDHB gene is inherited in an autosomal dominant manner and is associated with poor prognosis and increased metastatic potential.

Objectives: This case report aims to present the clinical course of a rare thyroid -SDHB related paraganglioma.

Methods-Results: The patient is a 54-year-old woman who underwent surgery for a thyroid nodule in 2016. Histopathological analysis of the thyroidectomy specimen unexpectedly revealed a paraganglioma, with a Ki-67 proliferation index of <1%. The patient had normal laboratory (plasma and 24-h urinary catecholamines) and imaging (neck-thorax-abdomen MRI/CT scan) results post-thyroidectomy. She was subsequently referred to our department after genetic testing identified a pathogenic mutation in the SDHB gene. Her family history includes a daughter with a benign Warthin’s tumor, another daughter who died from metastatic urothelial carcinoma, a third healthy daughter and a nephew with a carotid body paraganglioma. Genetic testing of her two living children was negative for pathogenic SDHB mutations. Follow-up tests of the patient in May 2024 including MRI of both neck and abdomen were normal and Positron Emission Tomography (PET) scanning with Ga-68 and 18F-FDG revealed no pathological uptake. The patient remains under close observation, without evidence of recurrence or metastasis, 9 years after surgery.

Conclusion: Thyroid paragangliomas remain exceptionally rare and represent a diagnostic challenge due to the limited data available. Vigilance is crucial, as these tumors may present with subtle symptoms or go unnoticed. The absence of guidelines and research, especially in the context of SDHB mutations, highlights the need for further investigation.