Lumps on the inner side of elbow may be caused by fibroma, lipoma, enlarged lymph nodes or localized subcutaneous cysts, etc., and the cause should be identified in time. 1. Fibroma: the lump on the inner side of the elbow joint may be a fibroma, formed by abnormal proliferation of fibrous connective tissue. 2. Lipoma: Lumps on the inside of the elbow joint may be caused by lipoma. Lipoma is the abnormal accumulation of subcutaneous fat tissue, the formation of tumor-like changes, usually easy to occur in the more fat parts. 3. Enlarged lymph nodes: when the patient’s immunity is lowered and infection occurs, it can cause inflammation and enlargement of lymph nodes. If the inflammation spreads to the inner side of the elbow joint, it will be manifested as a lump on the inner side of the elbow joint. 4. Localized subcutaneous cysts: If the lump is relatively large, it may also be caused by localized subcutaneous cysts. If there is a lump on the inner side of the elbow, it is recommended to consult a doctor in time to clarify the cause of the disease and give targeted treatment.