Malignant carotid body tumors: report of two cases and review of the literature.

Paragangliomas may arise in any area of the body where nonchromaffin paraganglia are situated. These include the glomus jugulare, the carotid body, and the retroperitoneum. Malignant behavior of these paragangliomas has been a controversial subject with most authors, who consider them to be benign tumors. Some authors have diagnosed locally recurrent and infiltrative tumors as malignant, whereas most require the demonstration of metastatic potential as the only criterion for malignancy. Two cases of metastasizing carotid body tumors are reported with a review of the literature on this unusual neoplasm.