From the Guidelines
The 3mm lesion located within the fat anterior to the psoas, caudal to the lower pole of the left kidney, is likely a benign finding that has matured over time, and no immediate intervention is required. This conclusion is based on the fact that the lesion was present on CT scans taken just 1.5 months after the partial nephrectomy for Stage 1 Chromophobe renal cell carcinoma and has not shown significant growth or changes suggestive of malignancy 1. The European Association of Urology guidelines on renal cell carcinoma suggest that active surveillance is a viable option for small renal masses, with a recommended serial imaging frequency of CT, MRI, or US at 3 and 6 months, then every 6 months up to 3 years, and annually thereafter 1. Given that the lesion has been present for 1.5 months after surgery and has matured over time, it is likely a pre-existing structure that has evolved naturally, rather than a new metastasis or recurrence of the renal cell carcinoma. Regular surveillance imaging should continue as per standard protocol for post-nephrectomy monitoring, but the maturation of such small lesions over time is common and often represents benign changes in the post-surgical area rather than disease recurrence 1. Key points to consider in the management of this patient include:
- The lesion's stable appearance over time, which suggests a benign nature
- The patient's history of partial nephrectomy for Stage 1 Chromophobe renal cell carcinoma, which indicates a low risk of recurrence
- The importance of continued surveillance imaging to monitor for any changes in the lesion or the development of new lesions
- The potential for benign changes in the post-surgical area, which can mimic recurrence or metastasis 1.
From the Research
Significance of the 3mm Lesion
The presence of a 3mm lesion located within the fat anterior to the psoas, caudal to the lower pole of the left kidney, on computed tomography (CT) imaging 1.5 months following partial nephrectomy for stage 1 Chromophobe renal cell carcinoma (RCC) is a finding that warrants consideration of several factors:
- The natural history of Chromophobe RCC, which generally has a favorable prognosis with a low tendency to progress and metastasize 2
- The possibility of local recurrence or metastasis, although rare, as reported in cases such as liver metastasis from Chromophobe RCC 18 years after initial diagnosis 3
- The role of imaging modalities like CT in monitoring disease progression and detecting potential recurrences, with studies exploring the use of dual-energy spectral CT for differentiating between Chromophobe RCC and other renal cell carcinoma subtypes 4
Clinical Implications
The clinical implications of this finding include:
- The need for ongoing surveillance and monitoring, as patients with Chromophobe RCC can experience late recurrences 3
- Consideration of the patient's overall clinical context, including the stage and grade of the initial tumor, as well as any potential risk factors for recurrence or metastasis 2
- The potential utility of advanced imaging modalities, such as dual-energy spectral CT, in characterizing the lesion and informing management decisions 4
Histopathological Characteristics
The histopathological characteristics of Chromophobe RCC, including its morphologic features and genetic profile, are important considerations in understanding the significance of the 3mm lesion:
- Chromophobe RCC is characterized by a distinct set of morphologic and genetic features, including losses of chromosomes 1,2,6,10,13,17, and 21, and mutations in genes such as TP53 and PTEN 5
- The eosinophilic variant of Chromophobe RCC can share overlapping features with oncocytoma or other oncocytic tumors, highlighting the importance of accurate diagnosis and characterization 5