379. ENLIGHTENMENT OF THE VENOUS ANATOMY OF THE ESOPHAGUS—AN ANOMALY CAPTURED UNDER MEDIASTINOSCOPY

Abstract

Abstract Distant organ metastasis often occurs early in the course of esophageal cancer development and is associated with a poor prognosis. The modes of metastasis include hematological and lymphatic routes. Although in the literature the venous outflow of the esophagus is described to occur through the esophageal vein into the azygous vein, which subsequently joins the superior vena cava, the detained anatomy of the venous and lymphatic systems of the esophagus remains to be further investigated. We aimed to elucidate the regional anatomy of the venous system surrounding the esophagus via mediastinoscopic esophagectomy. Between January 2021 to January 2022, six patients with early esophageal cancer without apparent distant metastasis underwent minimally invasive esophagectomy and posterior mediastinal reconstruction with mediastinoscopy in our hospital. Detailed anatomy was captured and the spatial relationship between the esophageal vein and its draining vein was assessed intraoperatively and thoroughly reviewed postoperatively for any anomalies. A venous anomaly was seen in one out of six patients where the esophageal vein drained into the left pulmonary vein rather than into the azygous vein. This anomaly was not detectable on the preoperative CT images. Hemostasis of the esophageal vein was achieved without major hemorrhage or injury to surrounding tissues. The esophageal specimen showed a localized ulcerative lesion in the midthoracic esophagus that was consistent with moderately differentiated squamous cell carcinoma, pT3N0M0 pStage IIB, with v1 and ly1 invasion. The patient will remain under surveillance for recurrence. Direct venous drainage into the systemic circulation may attribute to its high rates of distant metastasis in esophageal cancer. This mechanism supports the higher prevalence of metastasis to the liver over the lung, and relatively high rates of bone and brain metastases. Close attention should be paid when performing esophagectomy as injuries to the esophageal vein and inadequate hemastasis may result in catastrophic bleeding when a direct connection with the systemic circulation is present.