Abstract

Ectopic hamartomatous thymoma (EHT) is a rare and distinctive benign neoplasm of the lower neck. We here report on a case of EHT arising in the suprasternal area of 47-year-old male patient. The well-circumscribed mass measured 7 x 6 x 4 cm and it predominantly had a solid gray-white cut surface. Microscopically, the tumor consisted of spindle cells, epithelial nests, and mature adipose tissue. The epithelial component was arranged in anastomosing cords, solid nests and variable-sized cysts that were lined by squamous or cuboidal epithelium. The spindle cells revealed the myoepithelial immunohistochemical phenotype. There was no obvious thymic differentiation nor was any normal thymic tissue observed in our case. We think that EHT needs to be reclassified with using different nomenclature to designate its origin and histology. Further, pathologists and clinicians should be aware of the existence of this tumor in the lower neck so as not to mistake it for high-grade sarcoma or spindle cell carcinoma.

• Keywords: Thymoma;Hamartoma;Branchial arch;Mixed tumor;Immunohistochemistry