Primary Sclerosing Paraganglioma of the Thyroid Gland: A Case Report

Objectives: Paragangliomas are neuroendocrine tumors derived from extra-adrenal paraganglionic cells of the autonomic nervous system. Paragangliomas of the thyroid are rare, with only 28 cases reported in the literature. The sclerosing paraganglioma variant, characterized by marked stromal sclerosis and hyalinization, has scarcely been reported. Methods: A 36-year-old woman with a history of a 1-cm vagal schwannoma followed with serial magnetic resonance imaging presented with a new solitary 2.5-cm enhancing soft tissue mass in the left thyroid. Results: Ultrasound examination of the thyroid revealed a hypoechoic, hypervascular, malignant-appearing mass. Two fine-needle aspirations were insufficient for diagnosis, and the mass was deemed a lesion of undetermined significance with subsequent indeterminate molecular testing. A diagnostic left thyroid lobectomy was performed, and pathologic examination revealed a lesion consistent with a sclerosing paraganglioma. Conclusions: Sclerosing paragangliomas are rare tumors, and only 1 case involving a primary thyroid mass has been reported in the literature. Although the sclerosing variant has features suggestive of malignancy, the true incidence of malignancy is unknown, given the rarity of its presentation. However, given the overall benign nature of paragangliomas, the sclerosing variant is also likely benign, despite its malignant features on ultrasound and histopathologic examination.