Lymph nodes surrounding the inferior mesenteric vein

Purpose: In surgery for left colon cancer, there is no consistent idea about management of the inferior mesenteric vein (IMV). The IMV and its surrounding tissue is not considered as a subject of general dissection since the existence of the lymph nodes surrounding the IMV has not been clarified. The authors have previously encountered a case of descending colon cancer with metastasis to the lymph node surrounding the IMV. Based on this experience, the search for regional lymph nodes around the IMV was performed in 10 cadavers. Method: The tissue along the IMV was carefully examined in the cadavers. After gross observations, the IMV including the surrounding tissue was excised for microscopic search of the regional lymph nodes. Result: In 8 cadavers, lymph nodes surrounding the IMV were identified, and in 4 cadavers, the lymph nodes were located in the middle portion between the left colon artery and the splenic vein. Therefore, lymph nodes around the IMV were considered to exist at a relatively high frequency. Conclusion: Although lymph nodes around the IMV have been described in textbooks since the 1900s, they are not regarded as a significant issue in colon cancer surgery today. However, there is a possibility of metastasis of colon cancer to the lymph nodes along the IMV, if the left colonic lymphatic flow is obstructed in such tumor metastasis and the cancer cells travel through the accessory lymphatic path along the IMV. To clarify the clinical significance of the lymph nodes surrounding the IMV, the accumulation of future clinical data is necessary.