Mature teratoma of the mediastinum with mucinous adenocarcinoma (colloid carcinoma) - same case as the gross specimen shown in the previous image. Normal thymus is seen on the upper left. Pools of extravasated mucin from colloid carcinoma are on the upper right. A few intestinal-type glands can be seen near the bottom. The central portion shows xanthogranulomatous reaction caused by the mucin extravasation.