Paraganglioma of the thyroid: two cases that clarify and expand the clinical spectrum.
BACKGROUND: Paragangliomas (PGs) can, on rare occasions, arise within the thyroid parenchyma presumably from displaced laryngeal paraganglia. On the basis of a limited number of reported cases, thyroid PGs invariably affect women, they are always benign, and they are usually mistaken for some other more common thyroid lesion. METHODS: We describe the histopathologic features, immunohistochemical findings, and clinical characteristics of two thyroid PGs. RESULTS: One tumor was incidentally discovered in a 55-year-old man during evaluation of a carotid bruit. The other tumor aggressively invaded the trachea and esophagus of a 52-year-old woman with a presumed long-standing nodular goiter. In both cases, the initial pathologic evaluation suggested medullary thyroid carcinoma. Both patients are alive without recurrent disease after surgical resection. CONCLUSIONS: These cases emphasize the need to consider PG in the differential diagnosis of neuroendocrine thyroid tumors, even in those tumors involving men or behaving in a locally aggressive fashion. Failure to do so carries grave implications regarding patient prognosis and management.