Lymphedema is caused by obstruction of lymphatic fluid return to certain parts of the body. After repeated infection of tissue fluid on the body surface, the subcutaneous fibrous connective tissue proliferates and fat sclerosis is manifested as thickening, and later the skin thickens and becomes rough and tough like elephant skin, also called elephant skin swelling. The causes of lymphedema are as follows: First, primary lymphedema. Primary lymphedema can be typed as follows: 1. lymphatic dysplasia with subcutaneous lymphatic invasion; 2. lymphatic hypoplasia with small and few lymph nodes and lymphatic vessels; 3. lymphatic hyperplasia with large and many lymph nodes and lymphatic vessels, sometimes distorted and varicose, which is congenital. Second, secondary lymphedema. 1, infectious parasites, bacterial fungal infections can cause lymphedema; 2, injury surgery, radiotherapy burns, etc., can also cause lymphedema; 3, malignant tumors, primary tumors, secondary tumors, etc., can also cause lymphedema; 4, other, systemic diseases, pregnancy, etc., can also cause primary lymphedema, lymphedema is acquired, that is, secondary lymphedema. edema.