Newborns have hard lumps in the chest for 15 days, the causes are usually divided into physiological and pathological, physiological factors may be due to the influence of hormones, while pathological factors include inflammatory lumps and tumors. 1. Physiological factors: newborns may be affected by progesterone in the mother’s body, which leads to hard lumps in the breast. 2. Pathologic factors: (1) Inflammatory lump: It is considered to be an inflammatory lump caused by inflammatory infection, resulting in breast irritation. (2) Tumor: it mainly includes limited tumor as well as metastatic tumor, the chance of local tumor is relatively small, but if suffering from other malignant tumors, such as neonatal hepatocellular malignant tumor, soft tissue tumor, etc., which are not handled in time and metastasized to the chest, it will lead to hard lumps in the chest. If you find hard lumps in the chest of newborns, you should go to the hospital in time to do chest CT, ultrasound for diagnosis and analysis, and if necessary, you need to do pathological biopsy to analyze the cause of the disease, and then carry out treatment.