D. Ectopic hamartomatous thymoma
Ectopic hamartomatous thymoma is an unusual tumor that invariably occurs in the neck area. The tumor is more often found in adult men and rarely in women.
Characteristically, the tumor has a blend of spindle cells and adipose tissue, which on immunohistochemical studies may show positive staining for epithelial markers such as keratin. CD-34 and actin may also show positive staining; however, desmin is negative.
Complete surgical resection is the treatment of choice and the prognosis is good.