Lymphoma is usually diagnosed by biopsy, followed by whole-body CT examination to evaluate the whole body, the former can clarify the nature of the tumor, and the latter to check whether there are distant metastases and help staging. Biopsy, also known as pathology biopsy, is done first, in which a portion of tissue is taken from the lesion site under surgical or ultrasound guidance, stained under the microscope, and subjected to immunohistochemistry, which can clarify the pathology of the lymphoma, and then decide on the next step of the treatment plan. After the biopsy, a whole-body CT examination, usually referred to as PET-CT, is also needed, because whole-body CT can clarify the number and distribution of enlarged lymph nodes in the whole body, which is helpful for the staging of lymphoma, and also for the selection of treatment plan. After the above two tests, other tests will be performed under the doctor’s guidance to formulate a treatment plan.