Location: The most common location for thymomas is anterosuperior mediastinum. Thymomas account for 20% to 30% of all tumors in this location. Other sites include neck, within thyroid gland, pericardial cavity, pleura, pulmonary hilum, and within the lung parenchyma. This is a specimen of invasive thymoma, type B in a 52 y/o male. The image shows a whitish-grey lobulated tumor with infiltration of fat (lower right). Image copyright: pathorama.ch.