From the Guidelines
No, the fat anterior to the psoas muscle below the left kidney's lower pole is not part of the primary lymphatic drainage chain for renal cancer. Kidney cancer primarily drains through a predictable lymphatic pathway that begins with the hilar lymph nodes located at the renal hilum where blood vessels enter and exit the kidney, as discussed in the context of radical nephrectomy 1. From there, lymphatic drainage continues to the para-aortic lymph nodes adjacent to the aorta, and then to more distant retroperitoneal nodes. The fat anterior to the psoas muscle below the kidney's lower pole lies outside this established drainage pathway.
This anatomical understanding is important for surgical planning and staging of kidney cancer, as surgeons typically focus on removing lymph nodes along the primary drainage pathways when performing lymph node dissections, such as in the case of radical nephrectomy where regional lymph nodes dissection can be reserved for patients with clinically positive nodes detected by CT or during the surgical procedure 1. The lymphatic system follows relatively consistent anatomical patterns, which helps predict the most likely locations for metastatic spread in kidney cancer, and this particular area is not considered a primary site for lymphatic metastasis from renal cell carcinoma.
Key points to consider in the management of renal cancer include:
- The role of radical nephrectomy in the treatment of renal cell carcinoma, including the removal of kidney, perirenal fat tissue, adrenal gland, and regional lymph nodes 1
- The potential to spare the adrenal gland in patients with tumors ≤5 cm in size, located at the inferior pole 1
- The importance of regional lymph node dissection in patients with clinically positive nodes detected by CT or during the surgical procedure 1
- The use of cytoreductive nephrectomy in patients with metastatic disease, even while receiving systemic targeted therapies, which has been supported by data from the US National Cancer Data Base 1
From the Research
Lymphatic Drainage in Renal Cancer
The primary lymphatic drainage chain for renal cancer is not well-defined, with multiple lymphatic outflow channels [(2,3)].
Location of Lymph Nodes
Lymph nodes greater than 1 cm were found in various retroperitoneal sections, with a trend of suprahilar, intra-aortocaval, and retro-aortocaval lymph node enlargement 2.
Fat Anterior to the Psoas Muscle
There is no direct evidence to suggest that the fat anterior to the psoas muscle below the left kidney's lower pole is part of the primary lymphatic drainage chain for renal cancer. However, the psoas muscle has been identified as a rare location for metastasis of renal cell carcinoma 4.
Lymph Node Dissection
Lymphadenectomy is currently accepted as the most accurate and reliable staging procedure for the detection of lymph node invasion in renal cell carcinoma 3.
Examination of Hilar Fat
Microscopic examination of the hilar fat increased the number of lymph nodes recovered, but the identification rate of these nodes was low, and such microscopic nodes were invariably negative 5.
- The role of lymphadenectomy in the management of renal cell carcinoma is still not clearly defined [(3,5)].
- Lymph nodes were recovered in 38% of patients, with hilar lymph nodes recovered in only 22.5% of patients 5.
- Metastases were seen only in grossly identified lymph nodes, with all microscopic nodes being negative 5.