Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Childhood Vascular Tumors ?
    ### Response:
    Key Points
                    - Childhood vascular tumors form from cells that make blood vessels or lymph vessels.    - Tests are used to detect (find) and diagnose childhood vascular tumors.    - Childhood vascular tumors may be classified into four groups.
    