A small subcutaneous lump at the left rib cage may be subcutaneous lipoma, trauma, osteochondroma of the rib cage, costochondritis, etc. 1. Subcutaneous lipoma: it is mostly a limited lump with clear boundary and soft and movable texture. Usually there is no conscious symptom, but when the lump is big, it can press the nerve and cause pain. 2. Trauma: trauma leads to rib fracture or subcutaneous tissue injury, local blood vessel rupture, blood stasis and gradual formation of subcutaneous hematoma. There will be obvious pain when pressing. 3. Osteochondroma of ribs: superficial mass can be touched, which can cause local vascular and nerve compression symptoms. 4. Costal chondritis: mainly related to local soft tissue thickening, localized swelling and pain, pain aggravated by pressure. Subcutaneous lumps on the left side of the ribs can also be seen in other diseases, and it is recommended that the patient seek medical treatment in time to avoid delaying the condition.