Hard lumps inside male chest, consider that it may be related to breast hyperplasia, breast cancer, trauma and other factors. 1. Breast hyperplasia: Abnormal hormone level in male body, especially the increase of estrogen level, can promote the proliferation of breast tissue, resulting in hard lumps in male chest. 2. Breast cancer: affected by genetic factors, environmental factors, etc., the proliferation of breast epithelial cells is out of control, and the rapid proliferation of malignant tissues can also lead to hard lumps inside the chest of men. 3. Trauma: trauma to the male chest can form a local hematoma or cause tissue congestion and swelling, which can also lead to hard lumps in the male chest. Clinically, we should also consider benign breast tumors, chest wall diseases and other causes of hard lumps in male chest. It is recommended to go to the breast surgery or thoracic surgery department of the hospital as soon as possible to complete the relevant examinations to clarify the cause of the disease.