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 skin melanoma that is characterized by slow growth of a small pigmented spot on the skin with a clearly defined edge, surrounded by normal-appearing skin and occurs on occurs on non hair-bairing surfaces including hands and feet, subungual sites, and fingers or toes. (DO)