Ectopic Thymic Carcinoma Located on The Dorsal Side of The Thyroid Gland

Migration of the embryonic thymus is thought to be the basis for the formation of ectopic thymic tumors. Thymic ectopy may be a result of the abnormal migration of the third or fourth branchial cleft to the anterior mediastinum during weeks 5–6 of embryonic development. However, ectopic thymic carcinoma has highly nonspecific histologic features and occurs in variable and unpredictable locations making it difficult to diagnose. However, the clinical diagnosis and treatment should not overlook the possibility of ectopic thymic tumors. Here, we report a case of ectopic thymic carcinoma diagnosed as thyroid cancer before surgery occurring in a location consistent with current assumptions. Furthermore, we briefly review the literature on ectopic thymic carcinoma and discuss current diagnostic and treatment approaches.