Enlarged lymph nodes, usually caused by the infection of pathogenic microorganisms, can be enlarged and painful, you can see the Department of Infectious Diseases. Common pathogenic microorganisms are bacteria, viruses, rickettsiae, common diseases are: acute and chronic tonsillitis, cellulitis, respiratory infections, lymphatic tuberculosis. Lymph node enlargement can also be caused by tumor, you can see oncology, like lymphoma, leukemia, metastasis of tumor. When you visit the doctor, you can check the blood routine, bone marrow aspiration tumor can do pathological examination.