Four-year-old boy always shouting leg pain may be growing pains, trauma, rickets, leukemia, osteogenic sarcoma and other causes. 1. Growing pains: four-year-old boys grow and develop faster, which may cause bone pain, usually not accompanied by other abnormal symptoms. The pain site is commonly found in the front side of the calf, around the knee joint and so on, which is a normal physiological phenomenon. 2. Trauma: leg trauma may lead to leg muscle injury, bone injury, etc., which will cause redness, swelling, pain, bruising and other symptoms in the affected area. 3. Rickets: often caused by vitamin D deficiency, is a common disease in children, patients will appear irritable, excessive sweating, sleep disturbance, lower limb pain and other symptoms. 4. Leukemia: it is a malignant tumor disease of the blood system. With the development of the disease, patients will have symptoms such as bleeding, anemia, infection, and tingling in the legs. 5. Osteogenic sarcoma: it belongs to a kind of malignant tumor, patients will have lumps and pains in joints and bones, preferably in tibia, femur and other parts. The pain is especially obvious at night. Four-year-old boy always shouting leg pain may also be caused by other causes, it is recommended to take the child to the doctor as soon as possible, and follow the doctor’s instructions for treatment.