A 64-year-old man has symmetric pitting edema in both legs for 3 weeks. The edema worsens over the day and relieves after night sleep. He has no limitation of motion, no eyelid edema, no fever and no pain. And he is able to lie down at night. History of past illnesses: hypertension for several years and it is under control by oral amlodipine and metoprolol. Bp: 120/70mmHg. Physical exam reveals no abnormalities in his heart and lungs but mild pitting edema in his legs. Which of the following is UNLIKELY to be the diagnosis?