A 10 year old child develops a testicular mass and undergoes orchiectomy. On cut section, the mass shows a variety of appearances and colors. Histologically, many different tissues are seen, including cailage, thyroid, and neural tissue. A small focus of clear-cut squamous cell carcinoma is seen. Which of the following is the most appropriate classification for this tumor?
Dermoid cyst Embryonal carcinoma Immature teratoma Teratoma with malignant transformation