A 58-year-old male presents with incidental discovery of a left renal mass on CT abdomen done for unrelated abdominal pain. Imaging shows a golden-yellow mass in the upper pole of the left kidney (marked **A** in the diagram), with areas of hemorrhage and necrosis. Biopsy confirms clear cell renal cell carcinoma. On examination, the patient is noted to have a left-sided varicocele. Which of the following best explains the mechanism of the varicocele in this patient?