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 small, circumscribed, benign tumor of the genital tract, composed of small glandlike spaces lined by flattened or cuboidal mesothelium-like cells. (From Dorland, 27th ed)