From the Guidelines
The appearance of a nodule one month after partial nephrectomy for stage 1 chromophobe renal cell carcinoma (RCC) that remains visible on CT imaging for three years warrants further evaluation, and I recommend a biopsy of this nodule to determine if it represents recurrent cancer or benign tissue. The location in the fat anterior to the psoas muscle below the lower pole of the left kidney is concerning for potential local recurrence, though the stability over three years is somewhat reassuring 1. According to the ACR Appropriateness Criteria, most recurrences occur within 3 years after treatment, with a median time to relapse of 1 to 2 years, and the lungs are the most common site affected by metastases, followed by the lymph nodes, bones, liver, adrenal glands, and brain 1.
Key Considerations
- The patient's history of stage 1 chromophobe RCC and partial nephrectomy
- The nodule's location and stability over three years
- The need for thorough investigation to exclude malignancy
- The potential for benign processes, such as scar tissue
Recommended Course of Action
- Biopsy of the nodule to determine if it represents recurrent cancer or benign tissue
- If malignancy is confirmed, surgical excision would likely be recommended, potentially followed by surveillance imaging every 3-6 months for the first two years
- If benign, continued annual surveillance imaging would be appropriate
- Discussion with a urologic oncologist to develop a personalized management plan 1
Rationale
The American Society of Clinical Oncology clinical practice guideline recommends that any new nodule appearing post-surgery requires thorough investigation, and that chromophobe RCC typically has a favorable prognosis with low recurrence rates after complete resection 1. However, the stability of the nodule over three years suggests it may be scar tissue or a benign process, but malignancy cannot be excluded without tissue sampling. Therefore, a biopsy is necessary to determine the nature of the nodule and guide further management.
From the Research
Significance of a Nodule after Partial Nephrectomy
- The appearance of a nodule 1 month after partial nephrectomy for stage 1 Chromophobe Renal Cell Carcinoma (RCC) located in the fat anterior to the psoas muscle below the lower pole of the left kidney, still visible on Computed Tomography (CT) imaging 3 years later, may indicate a potential recurrence or residual tumor 2, 3.
- Chromophobe RCC is a subtype of renal cell carcinoma with a generally favorable prognosis, but a subset of patients may experience disease progression 2.
- The presence of a nodule in the fat anterior to the psoas muscle may suggest a possible local recurrence, which is a known complication of partial nephrectomy 2, 3.
Prognostic Factors
- Tumor size, pT stage, broad alveolar architecture, Fuhrman nuclear grade, microscopic tumor necrosis, vascular invasion, and sarcomatoid change are associated with disease progression in chromophobe RCC 2.
- The presence of sarcomatoid change, microscopic necrosis, and high pT stage are independent predictors of aggressive chromophobe RCC 2.
Diagnostic Challenges
- Distinguishing between renal oncocytoma and chromophobe RCC can be challenging due to their similar cellular origin and overlapping CT features 4.
- CT imaging features such as location, tumor size, relative density ratio, segmental enhancement inversion, necrosis, and perirenal fascia thickening can be useful in differentiating between renal oncocytoma and chromophobe RCC 4.