Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Adult Non-Hodgkin Lymphoma ?
    ### Response:
    Key Points
                    - Adult non-Hodgkin lymphoma is a disease in which malignant (cancer) cells form in the lymph system.    - The major types of lymphoma are Hodgkin lymphoma and non-Hodgkin lymphoma.    - Non-Hodgkin lymphoma can be indolent or aggressive.
    