From the Guidelines
The fat anterior to the psoas below the lower pole of the left kidney does contain lymph nodes and is an important part of the lymphatic drainage pathway for the kidneys. This area is a common site for metastatic lymph nodes from kidney cancer, as renal cell carcinoma typically spreads via lymphatic routes, and the lymphatic drainage of the kidneys follows a predictable pattern through the hilar, paracaval, para-aortic, and interaortocaval lymph nodes 1. The left kidney specifically drains to lymph nodes along the left renal vein, the para-aortic chain, and nodes anterior to the psoas muscle. Key points to consider include:
- The importance of evaluating this area during surgical management of kidney cancer, particularly radical nephrectomy with lymph node dissection, as it is often included in the lymphadenectomy field 1.
- The role of imaging studies such as CT scans with contrast in assessing this region when evaluating for potential metastatic disease from kidney cancer, as enlarged nodes in this location may represent the first sign of lymphatic spread.
- The recommendation for lymph node dissection for patients with palpable or CT-detected enlarged lymph nodes, and for those with normal-appearing nodes to obtain adequate staging information 1. Considering the potential for lymph node involvement and metastasis, it is crucial to carefully assess and manage this area in the context of kidney cancer treatment, prioritizing morbidity, mortality, and quality of life outcomes.
From the Research
Lymph Node Involvement in Renal Cell Carcinoma
- The presence of lymph node metastases in renal cell carcinoma (RCC) is a significant prognostic factor, doubling the patient's risk of distant metastasis and reducing their 5-year survival rate 2.
- Lymph node involvement in RCC can be evaluated using various modalities, including color Doppler sonography, magnetic resonance imaging (MRI), lymphotrophic nanoparticle enhanced MRI, multidetector-row computed tomography (MDCT), F-fluoro-2-deoxyglucose positron emission tomography (FDG-PET), and PET/CT 2.
- MRI has been shown to have the highest sensitivity (92-95.7%) for detecting lymph node involvement in RCC, while FDG-PET has the highest specificity (100%) for confirming lymph node involvement and extent of involvement 2.
Fat Anterior to the Psoas Major and Lymph Node Involvement
- There is no direct evidence in the provided studies to suggest that the fat anterior to the psoas major below the lower pole of the left kidney contains lymph nodes or participates in the lymphatic chain for the kidneys.
- However, studies have shown that lymph node metastases in RCC can occur in various locations, including the renal hilus, para-aortic, and paracaval regions 3, 4.
- The presence of enlarged lymph nodes in the vicinity of the kidney does not always indicate metastatic disease, as inflammatory changes and/or follicular hyperplasia can also cause lymph node enlargement 4.
Metastatic Lymph Nodes from Renal Cancer
- Metastatic lymph nodes from renal cancer can occur in various locations, including the retroperitoneal lymph nodes 5, 3.
- The study by 3 found that subdiaphragmatic lymph node metastases were associated with poor prognosis in metastatic RCC patients treated with targeted therapies.
- The study by 4 found that enlarged lymph nodes in patients with RCC were often not due to metastases, but rather inflammatory changes and/or follicular hyperplasia.