Incorrect. An aortic aneurysm could press on other structures resulting in edema, but this is not likely to occur so quickly after the thoracic surgery and it is further unlikely that the radiology imaging involved in planning an esophageal cancer thoracic surgery would have missed an aneurysm sufficiently large to be impinging nearby structures.

Incorrect. Blockage of the esophagus would cause difficulties with swallowing, not lower limb edema or intestinal discomfort (indeed the intestines would become empty due to an inability to consume foods/liquids).   

Correct! The thoracic duct is located in the posterior mediastinum. Thoracic surgery involving the mediastinum could have injured this duct.  As the duct returns lymph from all regions inferior to the diaphragm, this would cause abdominal and lower limb edema consistent with the reported symptoms.

Incorrect. Pleural effusion is the build-up of fluid in the pleural space decreasing available space for the lung. This would not affect the lower extremities.

Incorrect. While cancer metastasis is possible with esophageal cancer, the growth rate of cancers is slow and not likely to cause symptoms acutely.  More likely a cancer would give a slow progression of symptoms over months as the cancer starts to impinge/compress adjacent structures causing the symptoms.

Incorrect. Blockage of the azygos vein has limited consequences due to multiple anastomotic connections and alternative pathways blood can take to return to the heart. Most lower extremity blood returns via the inferior vena cava so blockage would have little to no impact on the limbs. The posterior intercostal veins would no longer drain to the azygos, but they would drain into the anterior intercostal veins, then the internal thoracic vein, and onto the subclavian vein. Thus, even the chest wall would have intact drainage in this case.

Incorrect. Nerve injury would cause gastrointestinal dysfunction that could explain the abdominal discomfort symptoms, but the vagus nerve does not project to structures other than organs. Thus, there are no vagus connections to the lower extremities (indeed, there are no parasympathetic connections to the limbs or body walls).