A lump on the head generally refers to a lump on the scalp, and the possible clinical causes are infection, benign head swelling, trauma, and so on. 1. Infection: when the hair follicles of the scalp are infected by pathogenic bacteria, such as bacteria, fungi, the affected area will have an inflammatory reaction and the formation of hard knots, the clinical manifestations of the affected area appear red, swollen, hot, pain and other symptoms. 2. Benign head swelling: this kind of situation is common in clinic, such as lipoma, sebaceous cysts, etc. People suffering from this kind of disease usually do not have obvious pain, and there is no pain symptom when pressing the swelling, and the mobility of the swelling is better, and the texture is hard. 3. Trauma: when the head is hit by external forces, local tissue damage and hematoma, bruising and so on, accompanied by obvious pain, pressure pain, etc.; with the passage of time, the pain symptoms will disappear. It is recommended that people with related conditions, especially those with obvious pain symptoms, should go to the hospital for examination to make a clear diagnosis, so as to follow the doctor’s instructions for targeted treatment.