A xanthoma is a nodule or maculopapular rash that resembles a tumor in nature. It often occurs in the area of the skin or tendons and is yellow in color. Xanthomas mainly contain fatty tissue as well as macrophage infiltration. They may be caused by a genetic history, or secondary to diabetes or thyroid dysfunction. It usually leads to localized pain and swelling, limitation of movement, and elevated blood lipids. Conservative treatment can be given with lipid-lowering drugs, and surgery can be performed if necessary.