Pressing pain in the armpit down to the ribs can be seen in soft tissue contusion, muscle strain, rib fracture, breast hyperplasia, mastitis and so on. 1. Soft tissue contusion: if the rib cage under the armpit has suffered impact injury and other traumatic injuries, there are soft tissue contusions such as bruises, subcutaneous hematomas, etc., there will be pressure pain. 2. Muscle strain: If the muscle here is strained due to excessive exercise, it will also cause pain when pressed. 3. Fractured ribs: Fractured ribs will cause obvious pain and deformity visible to the naked eye. 4. Breast hyperplasia and mastitis: Pressing on the rib cage under the armpit of a woman is also commonly associated with breast hyperplasia or mastitis. Breast hyperplasia is cyclical and the pain is more pronounced before menstruation, while mastitis is often accompanied by an increase in skin temperature, redness and swelling of the skin, and swelling of the lymph nodes in the armpit. There are many reasons for pain in the armpit down to the ribs by pressing, so if you have pain in this area, it is recommended to go to the hospital for further examination to clarify the cause of the pain and determine the next step in the treatment program.