From the Guidelines
The 3mm nodule in the fat anterior to the psoas muscle is likely a benign post-surgical change rather than a recurrence of renal cell carcinoma, and continued routine surveillance imaging is appropriate. This recommendation is based on the fact that the nodule has been stable in size over time, which is reassuring, as differences of 3.1 mm for inter-observer or 2.3 mm for intra-observer evaluations are within the variability of measurement and should not be attributed to tumor growth, unless there are persistent increases over two or more interval exams 1. The original chromophobe RCC was a favorable subtype with no aggressive features and was completely removed at an early stage, which carries an excellent prognosis. Regular follow-up scans should continue as scheduled to monitor the nodule, as recommended by the American Urological Association and other international oncologic and urologic societies, which suggest that patients undergo cross‐sectional abdominal scanning (CT or MRI) within six months of active surveillance initiation to establish a growth rate, and continued imaging (US, CT or MRI) at least annually thereafter 1. Key points to consider in the management of this patient include:
- The small size of the nodule and its stability over time
- The benign nature of the original chromophobe RCC
- The excellent prognosis associated with early-stage RCC
- The importance of continued routine surveillance imaging to monitor for any changes in the nodule or the development of new findings. Given the current evidence, continued routine surveillance imaging is the most appropriate course of action, rather than additional intervention, as the benefits of reducing ionizing radiation and intravenous contrast exposure should be weighed against the superiority of CT or MRI to evaluate perirenal or sinus fat invasion and lymph node involvement 1.
From the Research
Clinical Significance of a 3mm Nodule
The clinical significance of a 3mm nodule in the fat anterior to the psoas muscle, which appeared after partial nephrectomy for a 1.3cm chromophobe renal cell carcinoma (RCC), is uncertain.
- The nodule's small size and stability on subsequent scans suggest that it may be benign, but its appearance after surgery for RCC warrants careful monitoring.
- Studies have shown that chromophobe RCC has a favorable prognosis, with low rates of metastasis and cancer-specific death 2, 3.
- However, there is a risk of recurrence, even many years after initial treatment, and metastasis to unusual sites such as the duodenum has been reported 4.
- The presence of a nodule in the fat anterior to the psoas muscle could be a sign of local recurrence or metastasis, but further evaluation is needed to determine its nature and significance.
Prognostic Factors for Chromophobe RCC
Several studies have identified prognostic factors for chromophobe RCC, including:
- Gender, clinical T stage, pathological T stage, and presence of sarcomatoid differentiation, which were independent predictors of recurrence-free survival (RFS) and cancer-specific survival (CSS) in one study 2.
- N/M stage, which was also an independent predictor of CSS in the same study 2.
- The presence of collecting duct carcinoma and sarcomatoid components, which has been reported in a single case study and may be associated with a poorer prognosis 5.
Monitoring and Follow-up
Given the uncertainty surrounding the 3mm nodule, careful monitoring and follow-up are essential to determine its significance and to detect any potential recurrence or metastasis early.
- Regular imaging studies, such as CT scans, should be performed to monitor the nodule's size and stability.
- Any changes in the nodule's size or appearance should be thoroughly evaluated, and biopsy or other diagnostic procedures may be necessary to determine its nature and significance.