From the Guidelines
No, the fat located anterior to the psoas and below the lower pole of the left kidney is not part of the lymphatic chain for kidney cancer. This area contains perirenal fat and retroperitoneal fat that is separate from the lymphatic drainage system of the kidney. The primary lymphatic drainage for kidney cancer involves the hilar, para-aortic, and paracaval lymph nodes, as discussed in the context of radical nephrectomy for renal cell carcinoma 1. Kidney cancer typically spreads lymphatically through nodes adjacent to the renal hilum, then to the para-aortic nodes at the level of the renal vessels, and subsequently to retroperitoneal lymph nodes along the great vessels. The fat pad in question is anatomically distinct from these lymphatic pathways.
In the management of renal cell carcinoma, the focus of lymph node dissection is on the hilar and para-aortic regions rather than the fat anterior to the psoas muscle, as evidenced by the approach to radical nephrectomy which may include the removal of kidney, perirenal fat tissue, adrenal gland, and regional lymph nodes 1. Understanding the correct lymphatic drainage patterns is crucial for guiding appropriate staging and treatment decisions for patients with renal cell carcinoma. The distinction between different types of fat and their relationship to lymphatic drainage is important for surgical planning and ensuring that interventions are targeted effectively to improve patient outcomes in terms of morbidity, mortality, and quality of life.
From the Research
Lymphatic Chain for Renal Cancer
The fat located anterior to the psoas muscle and below the lower pole of the left kidney is part of the lymphatic chain for renal cancer.
- The lymph nodes in this region are part of the subdiaphragmatic lymph nodes, which are associated with a poor prognosis in patients with metastatic renal cell carcinoma (mRCC) treated with targeted therapies 2.
- The presence of lymph node metastases below the diaphragm is associated with shorter survival outcome when mRCC patients are treated with targeted therapies 2.
- Lymph node dissection at the time of radical nephrectomy for high-risk clear cell renal cell carcinoma may improve outcomes in high-risk RCC patients, and the lymph nodes from the ipsilateral great vessel and the interaortocaval region should be removed from the crus of the diaphragm to the common iliac artery 3.
- Enlargement of regional lymph nodes in renal cell carcinoma is often not due to metastases, but rather inflammatory changes and/or follicular hyperplasia, especially in the presence of tumor necrosis 4.
- Fat-containing renal tumors, including renal cell carcinomas, can be a diagnostic dilemma, and the presence of intratumoral fat is characteristic of angiomyolipomas, but can also be seen in renal cell carcinomas 5.
Lymph Node Metastases
Lymph node metastases are a common feature of renal cell carcinoma, and the location of these metastases can affect patient outcomes.
- Subdiaphragmatic lymph node metastases are associated with a poor prognosis in patients with mRCC treated with targeted therapies 2.
- The presence of lymph node metastases below the diaphragm is associated with shorter survival outcome when mRCC patients are treated with targeted therapies 2.
- Lymph node dissection at the time of radical nephrectomy for high-risk clear cell renal cell carcinoma may improve outcomes in high-risk RCC patients 3.
Diagnostic Considerations
The diagnosis of lymph node metastases in renal cell carcinoma can be challenging, and imaging studies such as computed tomography scans can be helpful in identifying enlarged lymph nodes.
- However, enlargement of regional lymph nodes in renal cell carcinoma is often not due to metastases, but rather inflammatory changes and/or follicular hyperplasia, especially in the presence of tumor necrosis 4.
- A dedicated computed tomography scanning protocol and strict diagnostic criteria are mandatory for accurate diagnosis of fat-containing renal tumors, including renal cell carcinomas 5.