Ectopic cervical thymoma--the great mimic: a case report.

Ectopic cervical thymoma is a rare tumour that probably arises from thymic tissue trapped during the migration of the thymus into the anterior mediastinum from the third and fourth pharyngeal pouches. As it occurs in the region of the thyroid gland it mimics thyroid lesions and can cause confusion to the clinician, sonologist and cytologist. Misinterpretation of frozen sections can also occur if knowledge of this entity is not present. We are reporting a case of this rare entity in an elderly lady who presented with a neck mass that mimicked a thyroid lesion. Ectopic cervical thymoma should be considered in the list of differential diagnosis of neck masses in the elderly.