The authors report an example of an unusual lower neck lesion, ectopic hamartomatous thymoma. Like other examples of this entity, the lesion was well marginated and characterized by cysts lined by squamous epithelium, adipose tissue, and spindle cells. The lesion was initially mistaken for a malignant neoplasm (at the time of frozen section) and the correct interpretation was rendered upon review of the permanent sections. They review the literature and clinicopathologic differential diagnosis of this entity.
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