Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Hemangioendothelioma ?
    ### Response:
    The term hemangioendothelioma describes several types of vascular neosplasms and includes both non-cancerous (benign) and cancerous (malignant) growths. The term has also been applied to those that show "borderline" behavior, intermediate between entirely benign hemangiomas and highly malignant angiosarcomas.
    