Pleomorphic adenoma arising in an incidental midline isthmic thyroid nodule: a case report and review of the literature.

Ectopic salivary gland tissue is common in the head and neck, usually associated with lymph nodes in lateral areas. It is rarely noted in the thyroid gland. Here we report the first case of a pleomorphic adenoma presenting as a midline nodule in the isthmus of thyroid in a 66-year-old man. We propose the possibility of origin in ectopic salivary gland tissue that may have aberrantly migrated with the median anlage from the foramen cecum in the base of the tongue during embryogenesis.