From the Guidelines
The fat anterior to the psoas muscle below the lower pole of the kidney, referred to as retroperitoneal fat, is indeed an uncommon location for renal cell carcinoma (kidney cancer) metastasis. This is because kidney cancer typically metastasizes to the lungs, bones, liver, brain, and adrenal glands through hematogenous spread, as noted in the NCCN Guidelines for Kidney Cancer 1. The retroperitoneal fat anterior to the psoas muscle represents a compartment that is anatomically distinct from the kidney's immediate surroundings. While local extension of kidney cancer can involve perinephric fat directly surrounding the kidney, spread to the more distant retroperitoneal fat anterior to the psoas muscle and inferior to the kidney is not a common metastatic pattern.
Some key points to consider in evaluating the spread of kidney cancer include:
- The primary sites of metastasis for kidney cancer, which are the lungs, bones, liver, lymph nodes, adrenal gland, and brain, as outlined in the NCCN Guidelines 1
- The role of venous drainage through the renal vein and inferior vena cava in the spread of kidney cancer to distant sites
- The anatomical distinction between the retroperitoneal fat anterior to the psoas muscle and the perinephric fat directly surrounding the kidney
Given the information from the most recent and highest quality study available, the focus for evaluating kidney cancer spread should be on the common metastatic sites rather than the retroperitoneal fat anterior to the psoas muscle 1. This approach is supported by the NCCN Guidelines for Kidney Cancer, which provide multidisciplinary recommendations for the clinical management of patients with clear cell RCC and nonclear cell RCC.
From the Research
Location of Metastasis
- The fat anterior to the psoas muscle below the lower pole of the kidney is referred to as retroperitoneal fat.
- There is limited information available on whether this location is uncommon for renal cell carcinoma (kidney cancer) metastasis.
Related Studies
- A study from 1987 2 discusses the technique of excision of the entire psoas major muscle via the retroperitoneal route, but does not provide information on the frequency of metastasis in this location.
- Studies from 2017 3, 4 and 2013 5 focus on the treatment of metastatic renal cell carcinoma, but do not mention the specific location of metastasis in relation to the psoas muscle.
- A study from 1994 6 examines the position of the bowel in the pararenal space, including the area between the kidney and the psoas muscle, but does not provide information on the frequency of metastasis in this location.
Metastasis Location
- The available studies do not provide direct evidence on whether the retroperitoneal fat anterior to the psoas muscle is an uncommon location for renal cell carcinoma metastasis.