The definitive diagnosis of malignant lymphoma relies primarily on lymph node biopsy. Fine-needle aspiration cytology is inaccurate and unable to distinguish subtypes. Fine-needle aspiration cytology does not provide a comprehensive and accurate diagnosis and requires biopsy. A biopsy is required unless there is a deep lesion without enlargement of superficial lymph nodes. Lymph nodes of moderate size (about 2-3CM) should be selected for biopsy, as too large tissue is prone to necrosis and too small pathological structure is not typical. The lymph nodes should be excised intact, not squeezed and not broken during surgery, and fixed in neutral formalin (not fixed in alcohol, because alcohol can affect the maintenance of surface markers of tumor tissue). Try to choose the lymph node biopsy from the area less disturbed by inflammation in the following order: supra-sliding lymph node, middle and lower neck lymph nodes, sub-chin lymph nodes, axillary lymph nodes, inguinal lymph nodes. Enlarged submandibular lymph nodes are most often associated with inflammation in the oral cavity, and enlarged inguinal lymph nodes are often associated with lower extremity infections such as tinea pedis infection.