Dr. CARLO A. BRAVI Urologist and Andrologist
Understanding Kidney Masses
A kidney mass (or renal mass) refers to an abnormal growth in the kidney. These growths can vary in size and type. While some are benign (non-cancerous), others may be malignant (cancerous), requiring prompt medical attention.
Common Types of Kidney Masses
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Simple cysts: Fluid-filled sacs, usually benign and often found incidentally.
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Angiomyolipomas: Usually benign tumors made up of fat, muscle, and blood vessels.
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Complex Cysts (Bosniak classification): These fall between simple benign cysts and potentially malignant tumors. Depending on their characteristics and Bosniak category, they may require monitoring or treatment due to an increased risk of cancer.
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Solid Tumors: Can be benign (e.g., oncocytomas) or malignant (e.g., renal cell carcinoma).
How Are Kidney Masses Diagnosed?
Many kidney masses cause no symptoms and are found during imaging for other reasons (technically called incidental findings). When symptoms occur, they may include:
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Blood in urine
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Pain in the side or back / palpable lump in the abdomen (advanced cases)
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Fatigue or unexplained weight loss (less common)
The diagnosis of kidney masses involves a combination of medical history, physical examination, imaging studies, and sometimes lab tests or biopsy. These steps help differentiate benign conditions, such as cysts, from malignant tumors or other kidney-related disorders.
Diagnosis begins with imaging tests:
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Ultrasound: Typically the first-line imaging test. Can detect cysts and distinguish them from solid tumors.
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CT or MRI scan: more detailed imaging to determine the nature, size, and spread.
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Biopsy: in selected cases, a needle biopsy may be done to confirm the diagnosis.
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Nuclear Medicine Scan (Renogram): a specialized test used to evaluate how well each kidney is functioning individually, also known as assessing “split renal function.”
Dr. Bravi’s approach begins with a comprehensive review of your medical history, including any prior imaging, family history of kidney disease or cancer, and general health factors. Attention is given to symptoms such as flank pain, blood in the urine, or fatigue. Based on the evaluation, appropriate imaging—such as ultrasound, CT scan, or MRI—is arranged. In some cases, further testing or referral for biopsy may be recommended to guide next steps.
Treatment Options
Treatment depends on the type and size of the mass, as well as the patient’s overall health:
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Small, benign, or slow-growing masses may be watched over time with regular imaging (active surveillance).
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Based on the characteristics of the kidney mass, patients may be offered either a partial nephrectomy (removal of the tumor while preserving the remaining kidney) or a radical nephrectomy (removal of the entire kidney). More detailed information on surgical interventions for kidney masses is available here.
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Minimally invasive options. Ablation (cryoablation or radiofrequency ablation) destroys the tumor with cold or heat, often used in patients who aren’t surgical candidates.
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Other treatments. In malignant cases that have spread beyond the kidney, treatment may include systemic (whole body) medical therapy such as immunotherapy, targeted therapy, or participation in clinical trials.
When to See a Doctor
If you have symptoms or an imaging study reveals a kidney mass, it’s important to see a urologist or oncologist. Early detection improves outcomes.
