From the Guidelines
The 3mm nodule found in the fat anterior to the psoas muscle below the lower pole of the left kidney is most likely a benign postoperative change or scar tissue that developed after the partial nephrectomy, and no specific treatment is needed for this finding. This conclusion is supported by the fact that while it initially appeared to be new on 3-year follow-up imaging, review of earlier scans showed it was actually present 1 month after surgery 1. Such small nodules in the surgical field are common findings after kidney surgery and typically represent fibrosis, granulation tissue, or small hematomas that have organized over time.
Key Considerations
- The location of the nodule in the perinephric fat outside the kidney parenchyma further supports its benign nature as a post-surgical change rather than a concerning lesion.
- The American Urological Association (AUA) guidelines for follow-up after clinically localized renal neoplasms suggest that patients should undergo cross-sectional scanning (CT or MRI) with and without IV contrast at three and six months following ablative therapy to assess treatment success, but this does not directly apply to the scenario of a postoperative nodule after partial nephrectomy 1.
- The guidelines also recommend against further radiological scanning in patients who have radiographic confirmation of treatment success and no evidence of treatment-related complications requiring further imaging, which aligns with the decision not to pursue additional imaging for this benign-appearing nodule 1.
Surveillance Approach
- Continued routine surveillance imaging according to standard post-nephrectomy protocols is appropriate, but this specific finding does not warrant additional intervention or more frequent imaging.
- The focus should remain on monitoring for any signs of recurrence or new pathology, following the principles outlined for post-treatment surveillance in patients after renal surgery, with adjustments based on individual patient risk factors and the specifics of their surgical and medical history 1.
From the Research
Nodule Significance
The significance of a 3mm nodule located in the fat anterior to the psoas muscle, below the lower pole of the left kidney, is uncertain based on the provided studies.
- The nodule's location and size do not directly match the characteristics of the nodules discussed in the studies, which primarily focus on pulmonary nodules or renal masses.
- However, some general insights can be gathered from the studies:
- Small nodules are more likely to be benign, as seen in the study on pulmonary nodules 2 and the study on echogenic renal masses 3.
- The study on pulmonary nodules 2 suggests that nodules smaller than 6 mm have a low probability of malignancy, and those 6 mm to 8 mm can be followed with repeat chest CT in 6 to 12 months.
- The study on echogenic renal masses 3 found that small echogenic renal masses up to 1 cm in size are rarely malignant and can be safely ignored.
Relevance to the Nodule in Question
- The nodule in question is located in the fat anterior to the psoas muscle, which is not directly related to the pulmonary or renal nodules discussed in the studies.
- However, the general principle that small nodules are more likely to be benign may still apply.
- The fact that the nodule was initially thought to be new on 3-year imaging follow-up but was later determined to be present 1 month post-operatively suggests that it may be a benign lesion that has been stable over time.
Management Options
- Based on the studies, it is unclear what the optimal management approach would be for this specific nodule.
- However, given its small size and stable nature, a conservative approach with serial imaging follow-up may be reasonable, similar to the approach suggested for small pulmonary nodules 2 or echogenic renal masses 3.