From the Guidelines
Lymph node metastasis in the fat anterior to the psoas muscle below the lower pole of the kidney, specifically the perirenal fat, is not an uncommon location for metastasis in renal cell carcinoma (kidney cancer). This is because renal lymphatic drainage commonly follows the renal veins to the para-aortic and paracaval lymph nodes, which can include nodes in this anterior parapsoas location 1. When evaluating for potential metastatic spread of kidney cancer, radiologists and oncologists typically assess multiple lymphatic drainage pathways, including hilar, paracaval, para-aortic, and interaortocaval regions.
Key Points to Consider
- The location of the primary tumor within the kidney influences the lymphatic spread pattern, with upper pole tumors often draining to paracaval or interaortocaval nodes, while lower pole tumors may drain to para-aortic nodes including those anterior to the psoas muscle 1.
- The NCCN Guidelines for Kidney Cancer provide multidisciplinary recommendations for the clinical management of patients with ccRCC and nonclear cell RCC (nccRCC), emphasizing the importance of understanding lymphatic drainage patterns for proper staging and surgical planning 1.
- Renal cell carcinoma primarily metastasizes to the lung, bone, liver, lymph nodes, adrenal gland, and brain, with lymph nodes being a common site for metastasis 1.
Clinical Implications
- Clinicians should be aware of the potential for lymph node metastasis in the anterior parapsoas region, particularly when evaluating patients with renal cell carcinoma.
- Accurate staging and surgical planning rely on a thorough understanding of lymphatic drainage patterns and potential sites for metastasis.
- The fat anterior to the psoas muscle below the lower pole of the kidney should be considered a potential site for lymph node metastasis in patients with kidney cancer, as it is not an uncommon location for metastasis 1.
From the Research
Lymph Node Metastasis in Renal Cell Carcinoma
- The location of lymph node metastasis in renal cell carcinoma (RCC) can vary, with some studies suggesting that the fat anterior to the psoas muscle, specifically the perirenal fat, is not a common location for metastasis 2, 3.
- However, other studies have found that lymph node metastasis can occur in the perirenal fat, although the frequency of this occurrence is not well established 4, 5.
- The patterns of lymph node enlargement in patients with metastatic RCC have been studied, with one study finding that two-thirds of nodes exhibited a suprahilar, intra-aortocaval, and retro-aortocaval trend of lymph node enlargement 3.
- Another study found that lymph node metastasis could be estimated in 188 out of 249 patients with RCC, with histologically confirmed lymph node metastasis classified as pN1 in 8 cases, pN2 in 7 cases, and pN3 in 5 cases 4.
- The role of lymph node dissection in RCC is still a topic of debate, with some studies suggesting that it may provide improved staging or a therapeutic advantage, while others argue that it may not be necessary for all patients 6.
Perirenal Fat and Lymph Node Metastasis
- The perirenal fat, which surrounds the kidney, is not typically considered a common location for lymph node metastasis in RCC 2, 3.
- However, one study found that enlarged lymph nodes in the perirenal fat were diagnosed on preoperative scans in 43 patients, with 18 of these patients (42%) having histologically confirmed metastases 5.
- The study also found that significant lymph node enlargement frequently may be caused by inflammatory changes, especially in the presence of tumor necrosis, rather than metastatic disease 5.