What is the clinical significance of a benign soft tissue mass and a stable 3 mm nodule in the fat anterior to the psoas muscle in a patient with a history of partial nephrectomy for chromophobe renal cell carcinoma?

From the Guidelines

The presence of a benign soft tissue mass and a stable 3 mm nodule in the fat anterior to the psoas muscle in a patient with a history of partial nephrectomy for chromophobe renal cell carcinoma does not indicate cancer recurrence, and therefore, no immediate intervention is needed. The patient's history and current findings are consistent with expected post-surgical changes, and the stability of the small nodule over time further supports its benign nature, as malignant lesions would typically grow more rapidly and substantially during this timeframe 1.

Key Considerations

• The 3 mm nodule has been present since one month after the nephrectomy and has not changed significantly, which is more consistent with post-surgical scarring or fibrosis rather than recurrent malignancy.
• The soft tissue mass in the paranephric space adjacent to the surgical bed is likely benign fat necrosis with mild chronic inflammation and fibrosis, which are expected post-surgical changes.
• The patient should continue with standard surveillance protocols for T1A RCC, which typically include imaging every 12 months for the first 3-5 years, then less frequently thereafter, as recommended by the American Society of Clinical Oncology 1.

Surveillance and Follow-up

• The patient's surveillance findings do not indicate cancer recurrence, and therefore, no changes to the current surveillance protocol are needed.
• The patient should be followed with annual imaging for the first 3-5 years, then less frequently thereafter, to monitor for any potential recurrence or new lesions.
• The use of cross-sectional scanning (CT or MRI) with and without IV contrast is recommended for surveillance, unless otherwise contraindicated, as stated in the AUA guideline 1.

From the Research

Clinical Significance of Benign Soft Tissue Mass and Stable 3 mm Nodule

• The presence of a benign soft tissue mass and a stable 3 mm nodule in the fat anterior to the psoas muscle in a patient with a history of partial nephrectomy for chromophobe renal cell carcinoma is not directly related to the primary tumor type 2, 3, 4, 5, 6.
• Chromophobe renal cell carcinoma (ChRCC) is generally considered to have a favorable clinical outcome, with a low risk of tumor progression and metastasis 3.
• However, some studies have reported cases of ChRCC with aggressive clinical behavior, including retrograde venous invasion and gain of chromosome 21 4.
• The clinical significance of a benign soft tissue mass and a stable 3 mm nodule in this context is not well-established, and further evaluation would be necessary to determine their relevance to the patient's history of ChRCC.

Prognostic Factors for ChRCC

• Patient gender, clinical and pathological tumor stage, and sarcomatoid differentiation are significant predictors of recurrence-free survival (RFS) and cancer-specific survival (CSS) for ChRCC 3.
• The presence of a benign soft tissue mass and a stable 3 mm nodule may not be directly related to these prognostic factors, but their presence could be relevant in the context of the patient's overall health and medical history.

Molecular Characteristics of ChRCC

• ChRCC is characterized by chromosomal aneuploidy, TP53, PTEN, and mitochondrial gene mutations 2, 6.
• The molecular characteristics of ChRCC are distinct from other kidney cancer subtypes, and further research is needed to understand their implications for patient outcomes and treatment strategies.