The appearance of hard lumps in the chest of boys is a common clinical phenomenon, the causes of which are mainly seen in the following areas: 1, as boys enter puberty, some children will have a transient chest development, mainly due to endocrine reasons, children in the breast will appear hard lumps, local bulge, when touched there will be obvious pressure pain, is a normal physiological phenomenon, parents do not need to worry too much, generally It lasts for 6-12 months and can be relieved by itself without special treatment; 2. Mastitis, such as bacterial infection in the child’s chest or trauma, can cause mastitis; 3. So if a boy has an obvious hard lump in his chest, it is recommended to go to the hospital and have a local ultrasound examination to clarify the nature of the hard lump.