Ewing sarcoma, found mostly in children and teenagers, is typically located in the leg bones and pelvis, but can occur in any bone. It may also form in the soft tissues of the chest, abdomen, arms, legs, or other locations.
Kaposi sarcoma (KS) is a type of cancer that forms in the lining of blood and lymph vessels and typically appears as painless purplish spots on the legs, feet, or face.
According to the American Cancer Society, Kaposi sarcoma is caused by infection with a virus called the Kaposi sarcoma-associated herpesvirus (KSHV), also known as human herpesvirus 8 (HHV8). KSHV is in the same family as Epstein-Barr virus (EBV), the virus that causes infectious mononucleosis (mono) and is linked to several types of cancer.