Hilar and mediastinal lymphadenopathy is common in mediastinal lymph node nuclei, lung cancer lymph node metastasis, malignant lymphoma, sarcoidosis, etc. The main points of differentiation are as follows: ① Tuberculous lymphadenopathy mainly occurs in the right trachea, trachea and bronchus, and carina, and the swollen lymph nodes can be seen with marginal enhancement after enhancement, and the center is relatively low density; Enlarged lymph nodes can have calcification. ② Most lymph node metastases of malignant tumors were larger than 2cm, and most of them showed uniform and consistent enhancement on enhanced scanning, and their locations were consistent with the lymphatic drainage of primary tumors. ③ Lymph node enlargement in malignant lymphoma is mostly caused by multiple groups of lymph nodes involved, merging into a group, surrounding and invading blood vessels. ④ The lymphadenopathy of sarcoidosis is mostly bilateral hilar lymph nodes distributed symmetrically in blocks.