A 68-year-old man is evaluated in the hospital due to a pleural effusion. He has a history of base of tongue squamous cell carcinoma with involvement of multiple left anterior cervical lymph nodes. Two days ago, the patient underwent surgery to remove the tumor and the anterior cervical lymph nodes. Today, he has increasing shortness of breath, and chest x-ray reveals a large left pleural effusion. Which of the following was most likely injured during this patient's surgical procedure?

Question

A 68-year-old man is evaluated in the hospital due to a pleural effusion.  He has a history of base of tongue squamous cell carcinoma with involvement of multiple left anterior cervical lymph nodes.  Two days ago, the patient underwent surgery to remove the tumor and the anterior cervical lymph nodes.  Today, he has increasing shortness of breath, and chest x-ray reveals a large left pleural effusion.  Which of the following was most likely injured during this patient's surgical procedure?

Quizplus · Accepted Answer

11ec160b_35da_b6d3_9249_bb51dabfa68a_MD0001_00 This patient with a pleural effusion 2 days after cervical lymph node removal most likely has a chylothorax due to intraoperative injury of the thoracic duct. The thoracic duct is the largest lymphatic vessel. It originates at about the level of T12 in the abdomen where the lumbar and intestinal lymph trunks converge. It travels superiorly through the mediastinum (posterior to the esophagus) and drains into the junction between the left subclavian and jugular veins in the lower neck. It is most commonly injured during thoracic procedures (eg, esophagectomy) but can be injured in neck procedures as well (eg, cervical lymph node removal). Injury can result in leakage of lymph into either the neck or the thorax because a transected duct may retract into the chest. The thoracic duct collects lymph from most of the body, including the abdominal viscera, the viscera of the left hemithorax, all tissue inferior to the umbilicus, and all left-sided tissues superior to the umbilicus (the right head, arm, and thorax drain into the much smaller right lymphatic duct). (Choices A and F) The trachea and esophagus are deeper structures in the central neck that are covered by strap muscles; they are unlikely to be injured during removal of cervical lymph nodes in the lateral neck. In addition, although injury to the esophagus or trachea can cause pleural effusion, such injury is typically accompanied by air accumulation (eg, crepitus in the neck and/or pneumomediastinum). (Choice B) The innominate artery is the first branch of the aortic arch, and it crosses the midtrachea from left to right (in the thorax). It does not travel through the left neck. In addition, injury to the innominate artery would cause massive blood loss, resulting in immediate hemodynamic instability. (Choice C) The apex of the lung can project into the neck and be injured in some neck surgical procedures. However, injury would cause an acute pneumothorax rather than a slowly accumulating pleural effusion. (Choice D) The phrenic nerve, which originates from C3-C5 and travels with the internal jugular vein, can be injured during neck procedures. However, such an injury would present with elevation of the hemidiaphragm. Educational objective: The thoracic duct carries lymph from most of the body and drains into the junction between the left subclavian and jugular veins. Although most commonly injured in thoracic procedures, it can also be injured in neck procedures where it travels through the neck. Injury may result in a chylothorax.

A 68-Year-Old Man Is Evaluated in the Hospital Due to a Pleural