A 44 year-old obese female reports pain in the right lower leg and thigh for the last few days. She reports a dull pain on the medial side of her right thigh (figure 1) and along the lateral surface of her right knee joint (figure 2). She has a history of varicose veins in both lower extremities. Her temperature is 99 °F (37.2 °C), heart rate is 78 beats/min, blood pressure is 140/92 mm Hg, respirations are 19 breaths/min, and oxygen saturation is 97% on room air. On examination, she is an obese woman. Physical examination is significant for induration, redness, and tenderness along the course of the local veins. The veins are erythematous, close to the surface, and palpable. There is erythema of the surrounding skin. Duplex ultrasound of the involved extremity reveals no deep venous thrombosis (figure 3). Figure 1 Which of the following is a true statement regarding this disorder?