If a patient experiences swelling and pain in the left subcostal spleen area, it may be due to diseases of the ribs and surrounding tissues, heart diseases, respiratory diseases, and diseases of the spleen itself. 1. Diseases of the ribs and surrounding tissues and trauma, such as rib fracture and splenic impact injury; local soft tissue contusion; in addition, intercostal neuralgia and so on can also cause swelling and pain in the left subcostal spleen area. 2. Diseases of the heart system, such as rheumatic heart disease, angina pectoris, coronary heart disease, acute myocarditis, acute pericarditis or cardiomyopathy, which may occur when blood circulation is insufficient. 3. Respiratory diseases and some digestive diseases, such as: left pneumothorax or left pleural effusion, and chronic gastritis or gastroesophageal reflux disease, will also appear this symptom. 4. Spleen diseases, such as benign cysts and benign and malignant tumors of the spleen. However, splenic diseases usually present hidden pain and need further examination to clarify. It is recommended to go to the hospital in time when symptoms occur, to clarify the cause of the disease and target treatment.