Paraganglioma of the thyroid: two cases that clarify and expand the clinical spectrum.

Abstract

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. We describe the histopathologic features, immunohistochemical findings, and clinical characteristics of two thyroid PGs. 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. 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.