Paraganglioma of the Thyroid: A Case Report

ABSTRACT

Paragangliomas (PGs) of the thyroid are very rare tumors. Based on the medical literature, thyroid PGs invariably affected women and they were always thought to be benign, and they have always been mistaken for other more common lesions. We report here on the first case of PG of the thyroid in a 45-year-old man in Korea. Ultrasonographically, the tumor showed hypoechoic features. Microscopically, the tumor showed the typical zellballen pattern. The small to medium-sized tumor cells contained moderate amounts of finely granular eosinophilic cytoplasm and round to oval nuclei with fine chromatin. The tumor invaded the thyroid capsule and the extrathyroidal tissue with vascular and perineural invasion. Immunohistochemically, the tumor showed positivity for chromogranin, S-100 protein, CD56a, and synaptophysin and negativity for calcitonin, thyroglobulin, galectin-3, p53, CK19, and EMA. The Ki-67 labeling Index was 10%. We concluded that our case has a high potential of metastasis, and a close follow up would be important.