A lump growing in the waist with pain and numbness may be due to sebaceous cysts, lipomas and other diseases, which need to be targeted treatment according to the cause of the disease. 1. Sebaceous cysts: As the sebum secreted by the sebaceous glands in the waist can not be normally discharged from the follicles, cysts are formed, which compress the surrounding tissues and appear as lumps, and also stimulate the nerves and pain and numbness, which can be treated by surgical excision in general. 2. Lipoma: subcutaneous lipoma consists of mature fat tissue and is a kind of benign tumor. It is a benign tumor, which appears as a hard lump with clear boundary in the waist, and will cause pain and numbness when it presses the peripheral nerves, and requires surgical treatment to remove the diseased tissues. There may be other reasons for the appearance of lumps in the waist accompanied by pain and numbness, so it is recommended to go to the hospital in time, improve the examination, make a clear diagnosis and timely treatment to avoid the development of the disease and jeopardize the health of the body.