LAUSR

A teratoma is a germ cell tumor (GCT) commonly composed of somatic tissues derived from at least 2 of the 3 germ layers, that is, ectoderm, endoderm, and mesoderm. Teratomas account for <10% of all mediastinal masses.1 The frequency of a mature teratoma in mediastinal masses is ∼6% (27/445)2, whereas the presence of hepatic tissues in a mature teratoma is extremely rare.3 Recently, 2 GCTs with hepatocellular carcinoma (HCC) components were reported: one was a testicular teratoma,4 and the other was a germinoma in the brain.5 To the best of our knowledge, this is the first report of a mature cystic teratoma with an element of HCC arising in the anterior mediastinum.