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 connective tissue benign neoplasm arising from the extraskeletal soft tissues near tendons and joints. It is a well circumscribed tumor characterized by the presence of chondrocytes, a lobulated hyaline cartilage growth pattern, and in some cases calcification. (DO)