From the Research
No, the fat anterior to the psoas muscle below the lower pole of the left kidney is not part of the lymphatic chain for the left kidney. The lymphatic drainage of the left kidney primarily follows the left renal vein and drains into the para-aortic lymph nodes located along the abdominal aorta 1. These lymphatic vessels travel with the renal vasculature in the renal hilum and then course medially toward the aorta. The fat anterior to the psoas muscle below the kidney's lower pole is primarily retroperitoneal fat that contains the ureter and some blood vessels, but it does not contain significant lymphatic drainage from the kidney itself. Some studies have described the anatomy of the psoas muscle and its surrounding structures, including the presence of a cleft beneath the psoas major that contains loose connective tissue and neurovascular structures 1. However, these findings do not suggest that the fat anterior to the psoas muscle is part of the lymphatic chain for the left kidney. Understanding the correct anatomical pathways of lymphatic drainage is important for staging renal malignancies and planning surgical interventions for kidney cancer. The most recent and highest quality study on the topic, published in 2022, provides detailed information on the anatomy of the psoas muscle and its surrounding structures, but does not support the idea that the fat anterior to the psoas muscle is part of the lymphatic chain for the left kidney 1. Other studies have described various pathologic processes that can involve the iliopsoas compartment, including inflammatory, hemorrhagic, and neoplastic conditions 2, but these findings are not relevant to the question of whether the fat anterior to the psoas muscle is part of the lymphatic chain for the left kidney. In summary, the available evidence suggests that the fat anterior to the psoas muscle below the lower pole of the left kidney is not part of the lymphatic chain for the left kidney, and the main lymphatic drainage of the kidney occurs at a higher level, near the renal hilum and along the course of the renal vessels.