A hard bump on the waist that is not painful or itchy is commonly caused by the following: 1. Lipoma, which is caused by the abnormal convergence of fat particles in the body, or sometimes caused by excessive body fat, is generally not a cause for concern and can be observed regularly if it does not increase significantly. The patient can go to the hospital for ultrasound and other clarifications, and only surgery can cure the disease. This is a benign disease that does not require special treatment or medication. 4. It may also be caused by swollen lymph nodes, often due to bacterial or viral infections, and rarely due to hematologic diseases or even malignant tumors. So if you have a swelling, you need to go to the hospital in time to clarify the cause and give treatment according to the results.