Small lymph nodes are a kind of description of lymph nodes in imaging or clinical examination, which mainly suggests that the size of lymph nodes is relatively small, and most of them belong to physiological changes. Excluding physiological factors, some people may also have small localized lymph nodes under the etiology of infections, immune system disorders and tumors. 1. Physiologic factors: Lymph nodes are distributed all over the body, and normal lymph nodes are relatively small in size and large in activity, which will not produce any symptoms. 2. Pathologic factors: (1) Infection: Lymph nodes belong to immune organs, and after infection occurs in the body, lymph nodes will increase in size and number, but their volume is still within the normal range, which belongs to small lymph nodes. (2) Immune system diseases: immune reactions in the body will also stimulate the lymph nodes, causing lymph nodes to increase in number and size, and in the early stage, they will also appear as small lymph nodes. (3) Tumor: mainly after metastasis of the primary tumor, small local lymph nodes will appear, and the corresponding lymph nodes are round, with small mobility and unclear demarcation with the surrounding tissues. After the discovery of small lymph nodes, it is mainly combined with clinical symptoms and clinical history to make a comprehensive judgment, and new lymph nodes should seek medical treatment in time under the guidance of clinicians for standardized treatment.