Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Lymphoma ?
    ### Response:
    Lymphoma is a cancer of a part of the immune system called the lymph system. There are many types of lymphoma. One type is Hodgkin disease. The rest are called non-Hodgkin lymphomas.    Non-Hodgkin lymphomas begin when a type of white blood cell, called a T cell or B cell, becomes abnormal.
    