Hidden pain in the left lower part of the rib cage is often considered intercostal neuritis, rib fracture, heart disease, pleurisy and so on. 1. Intercostal neuritis: manifested as pain in the distribution area of intercostal nerves, abnormal sensation, burning pain, pinprick pain, band-like distribution. 2. Rib fracture: due to external factors such as car accident impact, stick injury, strenuous exercise, etc., it may lead to rib fracture, chest pain, chest tightness and other symptoms, the pain is aggravated when coughing or changing position, and localized skin lesions or bruises can be seen. 3. Heart disease: such as coronary heart disease, coronary artery lumen narrowing or occlusion, manifested as pain in the precordial region, abnormal sensation and so on. 4. Pleurisy: such as tuberculous pleurisy, involving the left side of the pleura, may manifest as chest tightness, chest pain and other symptoms, mostly accompanied by low fever, night sweats and other systemic symptoms. There are other causes of pain in the lower left side of the rib cage, and it is recommended that patients seek medical treatment in time to avoid delaying their condition.