Primary intrathyroidal paraganglioma with metachronous carotid body tumor: report of a case and review of the literature.

A case of primary intrathyroidal paraganglioma is reported, and the light microscopic and immunohistochemical findings are described. Primary paragangliomas of the thyroid region are extremely uncommon and are therefore often confused clinically and histopathologically with more common intrathyroidal mass lesions. The diagnostic difficulties are underscored by the present case, which was misdiagnosed twice, firstly as a medullary thyroid carcinoma and secondly as a follicular thyroid carcinoma. Immunohistochemistry may be very helpful in arriving at the correct diagnosis. The case was further complicated by a second neck mass contralateral to the original thyroid nodule, which was interpreted as consistent with metastasis. The second lesions was proved angiographically and histologically to be a carotid body paraganglioma.