Ectopic hamartomatous thymoma: a case study and review of the literature.

Ectopic hamartomatous thymoma is a rare and distinctive tumor found in the deep soft tissues of the neck, which is characterized histopathologically by a mixture of spindle, epithelial, and adipose cell elements. We present a case of this lesion occurring in a 39-year-old male. The characteristic histochemical and immunohistochemical findings of these tumors are demonstrated. In addition, review of the reported histological, immunohistochemical and ultrastructural findings is presented together with a table of clinical findings in the tumors so far described. A brief discussion of theories of histogenesis and possible differential diagnosis is included.