Ectopic hamartomatous thymoma--a truly rare neoplasm: report of a case.

An ectopic hamartomatous thymoma is an extremely rare benign neoplasm that commonly occurs in the lower neck region. It has distinctive pathological features that include haphazardly arranged spindle cells, epithelial cells, and mature fat tissue. Its histogenesis is still controversial. This report presents a case of a 26-year-old man with ectopic hamartomatous thymoma in the left supraclavicular region, and discusses the current knowledge regarding this type of lesion. Clinicians as well as pathologists should be aware of the existence of this disease so that it can be identified correctly.