A protruding rib above the left breast may be related to local deformity, chondroma, lipoma, etc., and requires further differential diagnosis by a doctor. 1. Deformity: Congenital developmental abnormality, fracture healing resulting in deformity and other causes may lead to protruding ribs above the left breast. 2. Chondroma: If a chondromatous lesion develops on the upper left rib cage, it may protrude from the skin surface. 3. Lipoma: If a lipoma develops between the skin and muscle of the rib cage above the left breast, a lump may be found protruding. A lump protruding from the ribs above the left breast may also be costochondritis, rib tumors, etc. It is recommended to go to the regular hospital in time to clarify the cause of the disease and carry out standardized treatment under the guidance of the doctor to avoid delaying the condition.