Case description: male, 15 years old; swelling of both lower extremities for 1 year; aggravated by prolonged standing or walking, no obvious pain and other complaints; previous physical fitness, denied history of various chronic and infectious diseases; specialized examination: diffuse swelling of both lower extremities, indentation by acupressure, poor capillary filling at toe end, normal active and passive movement of knee and ankle joints. Preliminary diagnosis: venous insufficiency of the lower extremities? Lower extremity lymphedema? Liver insufficiency? Hypoproteinemia? Cardiac insufficiency? Complete general examination, such as liver and kidney function tests, cardiac ultrasound, lower extremity vascular ultrasound or angiography