A blood vessel tumor that is made up of different types of cells and has features that are both benign (not cancer) and malignant (cancer). Composite hemangioendotheliomas usually form on or under the skin on the arms or legs. They may also form on the head, neck, or chest. Composite hemangioendotheliomas may spread to nearby lymph nodes, but usually do not spread to other parts of the body. They may come back in the same place after treatment. They are most common in adults. Composite hemangioendotheliomas are a type of vascular tumor.