RGD uses the Human Disease Ontology (DO, https://disease-ontology.org/) for disease curation across species. RGD automatically downloads each new release of the ontology on a monthly basis. Some additional terms which are required for RGD's curation purposes but are not currently covered in the official version of DO have been added. As corresponding terms are added to DO, these custom terms are retired and the DO terms substituted in existing annotations and subsequently used for curation.
A thymus cancer that derives_from epithelial cells. The tumor cells in a thymic carcinoma look very different from the normal cells of the thymus, grow more quickly, and have usually spread to other parts of the body when the cancer is found. (DO)