Possible diseases of pleural effusion lower extremity edema are pulmonary heart disease, heart failure, tuberculosis, lung cancer, etc., not necessarily late in life. 1. Pulmonary heart disease: patients with this disease have difficulty in the return of blood to the lower limbs, which can cause lower limb edema. Due to the dilatation of capillaries in the lung tissue of patients with pulmonary heart disease, pleural effusion will occur. But this does not mean that the patient is in the late stage of life, through active and effective treatment, it can be controlled. 2. Heart failure: it is mainly due to heart failure, the decline of blood excretion function of the heart, resulting in systemic fluid retention, reflux difficulties, resulting in pleural effusion, lower limb edema and so on. Heart failure belongs to the end stage of heart disease. 3. Tuberculosis: this kind of patients will also have pleural effusion and lower limb edema, but it can be controlled through active treatment. 4. Lung cancer: in case of lung cancer patients with pleural effusion, it is possible that pleural metastasis has occurred, and most of the patients belong to the middle and late stages. Besides the above diseases, renal tuberculosis, renal failure and hypoproteinemia can also cause the above symptoms. If the above symptoms occur, it is recommended to go to the hospital in time to get a clear diagnosis and early and regular treatment.