A lump of flesh on the back may be related to lipoma, fibroma, flat warts and other causes, which need to be further differentiated and diagnosed by a doctor. 1. Lipoma: Normal fat-like tissue occurs between the skin and muscle on the back, which can cause a local bulging meat bag. 2. Fibroma: due to genetic, endocrine and other reasons can lead to the appearance of deep in the back, unclear boundaries, hard swelling. 3. Flat warts: If the skin on the back is infected with human papilloma virus, it can cause localized flat papules that protrude from the skin. It is recommended that the person who has a bump on the back go to the hospital in time to clarify the cause of the disease, under the guidance of the doctor to standardize the treatment, so as not to delay the condition.