👉 Chorioepithelial neoplasia, also known as choriocarcinoma, is a type of cancer that begins in the lining of the blood vessels. It's similar to a cancer that starts in the lining of the lungs, but it's more common because it can affect many different types of tissues and organs. Chorioepithelial neoplasia occurs when cells from one side of the body, called the chorion, grow into another part of the body.