Summary of Anatomy and Physiology of Perigastric Lymphatic System

and Chao-Hui Zheng¹

(1)

Department of Gastric Surgery, Fujian Medical University Union Hospital, Fuzhou, China

Abstract

At the end of the nineteenth century, the medical community realized that lymph node metastasis (LNM) is the most common pattern of metastatic spread in gastric cancer. Satisfactory results will not be achieved if gastrectomy alone is performed for patients with gastric cancer. Many European and American researchers began to study the lymphatic flow of the stomach and explore the characteristics of LNM. Dissection of the relevant lymph nodes (LNs) revealed that metastasis was not limited to the LNs around the stomach. Those located at the superior border of the pancreas and other sites were also frequently involved. In 1944, Kajitani indicated that LNs positioned along the celiac artery system were closely involved in metastasis of gastric cancer according to the outcomes of 166 patients with gastric cancer who underwent lymph node dissection. He also proposed the concepts of systemic lymph node dissection. According to these concepts, Kajitani led the Japanese Research Society in the first detailed anatomical study of gastric cancer, in which the researchers divided the perigastric LNs into groups and described the lymphatic drainage routes of the stomach. He then observed the distribution of the metastatic LNs and studied the tendencies of LNM from a histological viewpoint. These discoveries helped to establish the theory supporting systemic lymph node dissection for gastric cancer. This anatomical description of the lymphatic system of the stomach by Japanese researchers was a key step in the study of LNM in gastric cancer.

1.1 Lymphatic Drainage Routes of the Stomach

The lymphatic networks in the gastric walls communicate with one another and flow in a certain direction, draining into the perigastric lymphatic system in close proximity to the corresponding veins. However, lymphadenectomy is performed along the corresponding arteries, and the perigastric LNs are grouped and named according to the arteries. Therefore, the lymphatic drainage of the stomach is customarily divided into four areas according to the four feeding arteries of the gastric walls.

District I (right gastroepiploic artery (RGEA) group): This lymphatic network mainly drains the greater curvature of the lower half of the gastric body and the pylorus. Lymphatic vessels are abundant in this area. They drain into the infrapyloric LNs along the RGEA. Their efferent lymphatic vessels drain into the retropyloric and suprapyloric LNs, then into the hepatic LNs, and finally into the celiac artery LNs. Some of the lymphatic vessels along the gastroepiploic veins in front of the pancreatic head drain into the LNs located at the root of the middle colic vein (MCV) and superior mesenteric vein (SMV).
District II (left gastroepiploic and short gastric arteries group): This lymphatic network mainly drains the greater curvature of the left half of the gastric fundus and the greater curvature of the upper half of the gastric body. Lymphatic vessels are rare in this area. They drain into the splenic hilar LNs and pancreaticosplenic LNs located at the pancreatic tail along the gastrosplenic ligament. Most lymphatic vessels of the left half of the gastric fundus flow left and drain into the splenic hilar LNs, while those located at the posterior wall of the gastric fundus flow directly into the pancreaticosplenic LNs. Most lymphatic vessels of the left half of the gastric body at the greater curvature turn left along the left gastroepiploic artery (LGEA) and drain directly into the splenic hilar LNs. A few lymphatic vessels drain into the inferior left gastric LNs, then into the splenic hilar LNs, and finally into the celiac artery LNs.
District III (left gastric artery (LGA) group): This lymphatic network mainly drains the right half of the fundus, left half of the lesser curvature, and cardia of the stomach. Most lymphatic vessels of the right half of the gastric fundus drain into the paracardial and pericardial LNs, while a few lymphatic vessels flow into the retrocardial and pancreaticogastric LNs. They occasionally flow into the left diaphragmatic LNs. Most lymphatic vessels of the left half of the lesser curvature of the stomach drain into the superior gastric LNs, while a few drain directly into the pancreaticogastric LNs. The lymphatic vessels of the gastric cardia mostly drain into the paracardial, retrocardial, and pericardial LNs, while a few flow into the superior gastric and pancreaticogastric LNs. The paracardial, retrocardial, pericardial, and superior gastric LNs all drain into the pancreaticogastric LNs, then into the celiac artery LNs. This area plays an important role in the lymphatic drainage of the stomach.
District IV (right gastric artery (RGA) group): The RGA is thin and contains little blood. Lymphatic vessels are rare in this area, and few suprapyloric LNs are present along the RGA. This area mainly drains the lesser curvature of the gastric pylorus, and a few lymphatic vessels drain into the hepatic portal LNs along the hepatoduodenal ligament (HDL) in a reverse direction. However, most lymphatic vessels drain into the LNs around the common hepatic artery (CHA), then into the celiac artery LNs.

The lymph drainage routes differ between gastric stump cancer and general gastric cancer because these drainage routes and the anatomic structure of the remnant stomach are changed by the first operation. First, the LGA and/or its descending branch at the lesser gastric curvature is transected. This causes the flow of the lymph vessels along the LGA to change and course toward the right cardia, then drain into the celiac artery LNs. The lymph vessels at the greater curvature of the stomach mainly drain into the splenic hilar LNs and splenic artery LNs. Additionally, the lymph vessels in the remnant stomach communicate with one another and the surrounding organs. Lymph vessels of the gastric cardia and fundus can drain into the lower esophagus through the esophagogastric junction. Those in the distal gastric stump drain into the duodenal wall (Billroth I anastomosis) or jejunal wall (Billroth II anastomosis). Cancer cells can invade the LNs in the mesentery of the anastomotic site and metastasize to LNs located at the root of the mesentery, especially when distal gastrectomy with Billroth II anastomosis is performed. Studies have shown that if the LGA is preserved during the primary surgery, the lymph drainage routes of gastric stump cancer are identical to those of primary upper-third gastric cancer. The main lymph drainage of the remnant stomach begins at the lesser curvature of the stomach along the LGA. However, if the LGA is transected during the primary surgery, the lymph drainage of the remnant stomach mainly follows the greater curvature of the stomach instead of following the original route.

The lymph drainage of gastric stump cancer is classified into three routes: (1) The lymph drainage is along the LGA, posterior gastric artery, and splenic artery (SpA). (2) The lymph vessels drain into the duodenal wall or jejunal wall. (3) The lymph vessels drain into the intrathoracic LNs.

< div class='tao-gold-member'>

Only gold members can continue reading. Log In or Register to continue