Cervical chordoma masquerading as a thyroid neoplasm: a case report.

Chordomas are rare neoplasms of notochord derivation that arise along the craniospinal axis. Their incidence along the cervical spine and close proximity to the thyroid can pose diagnostic pitfalls. We report a case of a paraspinal mass juxtaposed adjacent to the thyroid with intranuclear inclusions of papillary carcinoma, abundant eosinophilic cytoplasm of an oncocytic lesion, and pleomorphism of anaplastic carcinoma that expressed thyroglobulin and emulated a malignant thyroid neoplasm. However, subsequent histological examination revealed a chordoma with perithyroidal soft-tissue invasion. This case highlights the significance of including chordoma in the differential diagnosis of a thyroid neoplasm and interpreting thyroglobulin reactivity warily, because its inadvertent tracking during fine-needle aspirates (FNAs) can produce false positive staining of nonthyroidal cells. Copyright 2005 Wiley-Liss, Inc.