Approach to Renal Masses

Initial Diagnostic Evaluation

The American Urological Association recommends obtaining high-quality multiphase cross-sectional imaging (CT or MRI with and without contrast) to characterize enhancement patterns, assess complexity, detect fat content, and clinically stage the lesion for all newly detected renal masses 1, 2, 3
Multiphase contrast-enhanced CT or MRI is mandatory to assess tumor complexity, degree of enhancement, presence/absence of fat, and anatomic relationships 1, 2, 3
Characterization must include evaluation for locally invasive features, venous involvement, and contralateral kidney status 4, 5
For suspected malignancy, obtain chest imaging to evaluate for thoracic metastases 1, 2, 3

Perform renal mass biopsy in three specific scenarios: prior to all thermal ablation procedures, when clinical/radiographic findings suggest lymphoma, abscess, or metastasis, and for indeterminate masses where histological diagnosis would alter management 1, 4, 6
The American College of Radiology endorses biopsy for diagnostic purposes to guide treatment decisions and minimize unnecessary kidney function loss 6

The American Urological Association recommends partial nephrectomy as first-line intervention when treatment is indicated for cT1a renal masses (≤4 cm) 1, 2, 3
Partial nephrectomy remains the priority nephron-sparing approach for cT1b renal masses (>4-7 cm) 1, 2, 3
Open radical nephrectomy with regional lymph node dissection is the standard approach for cT3a disease with nodal involvement 5

Prioritize nephron-sparing approaches (PN or TA) in scenarios such as anatomic or functionally solitary kidney, bilateral renal tumors, known familial RCC syndromes, pre-existing CKD (GFR <60), confirmed proteinuria, young patients, multifocal masses, and comorbidities likely to impact future renal function 1, 2, 3

Refer to nephrology when GFR <45 mL/min/1.73m², confirmed proteinuria is present, diabetics have pre-existing CKD, or expected post-intervention GFR <30 mL/min/1.73m² 1, 2, 3, 5
Radical nephrectomy increases risk of CKD, which correlates with increased cardiovascular morbidity and mortality 4

Recommend genetic counseling for all patients ≤46 years of age, patients with multifocal or bilateral renal masses, and those with personal or family history suggesting familial renal neoplastic syndrome 1, 2

Active surveillance with imaging every 1-3 years is the initial approach for bilateral angiomyolipomas with lesions <4 cm 8
mTORC1 inhibitors (everolimus or sirolimus) are first-line treatment when intervention is required for bilateral angiomyolipomas 8

Do not perform radical nephrectomy reflexively for cT1a masses; partial nephrectomy is greatly underutilized and often feasible even for central/hilar tumors with adequate expertise 4
Do not skip renal mass biopsy before thermal ablation—it is mandatory 1, 4
Do not ignore renal functional assessment—CKD staging must be performed for all patients with suspected malignancy 2, 3
Do not initiate treatment without high-quality cross-sectional imaging—inadequate imaging leads to suboptimal management decisions 1, 2
Do not perform systematic adrenalectomy unless direct adrenal involvement is demonstrated 5