What is Renal Mass?
Renal masses are unusual growths that occur in the kidney. While many of these growths are harmless, some of them may need further treatment. The kidney’s location and the signs and symptoms aren’t typically enough to identify these masses. Therefore, doctors commonly use imaging tests like CT scans, MRI, or ultrasound to diagnose them.
Renal masses are broadly divided into two categories: solid or cystic. This summary primarily focuses on the solid type, which often raises concerns of cancer. In 2019, there were approximately 74,000 new cases, with an expected 15,000 patients succumbing to this cancer.
When diagnosed early, the chances of surviving kidney cancer are significantly higher. For example, early-stage kidney cancer (stage 1 and 2) has a survival rate above 90%. In contrast, the rate drops below 15% for some advanced types of kidney cancer or when the disease has spread to other parts of the body.
It’s critical to identify and assess new renal masses promptly to improve patient outcomes and quality of life. One key indicator of cancer is the size of the tumor. Kidney masses are typically categorized into two sizes: smaller than 4cm and larger than 4cm. Because of improved imaging tests, more kidney masses are being discovered accidentally while checking for other health issues. For instance, a study conducted in 2011 found 14% of patients were incidentally diagnosed with kidney masses while undergoing CT scans for colon-related issues.
Given the complexity and variability of kidney masses, this summary will provide a detailed look at smaller kidney masses and examine the causes, diagnosis, and treatment of kidney masses.
What Causes Renal Mass?
Kidney masses, or tumors, can happen due to various reasons. For example, research has shown that smoking can increase the risk of a type of kidney cancer called renal cell carcinoma. Also, exposure to certain chemicals like benzene, herbicides, and vinyl are known to raise the risk of developing this cancer. Some medications, including certain non-steroidal anti-inflammatory drugs (pain and inflammation relievers), have been associated with an increased risk of kidney cancer. However, more research is needed to confirm these findings since the initial study was the first of its kind.
Your genetics can also play a role in the development of kidney masses. A common example is polycystic kidney disease, a condition where your kidney develops numerous cysts. This disease contains two forms, one that can be directly inherited from a parent (autosomal dominant) and another that requires both parents to have the gene (autosomal recessive). The latter tends to be more aggressive and often fatal. Both forms have a high likelihood of leading to aggressive kidney masses.
There are also certain specific disorders linked to the development of kidney masses. These include conditions called Von Hippel-Lindau and Birt-Hogg Dube syndromes. Interestingly, other conditions such as hepatitis C (a liver infection) and kidney stones (hard deposits formed in your kidneys) are also associated with renal cell carcinoma, a type of kidney cancer.
Risk Factors and Frequency for Renal Mass
Kidney and renal pelvic cancers rank as the 12th most common type of cancer in the United States. Men are more likely to be affected than women. People in mid-age, whether they’re White or Black, are equally likely to have these cancers while Asians are the least affected group. In 2019, there were about 7,400 cases reported according to the US census data. Around 15,000 lives are lost every year due to these cancers, with Renal Cell Carcinoma (RCC) responsible for 80% of the fatalities. With the increase in the use of advanced imaging techniques like MRIs and CT scans, more renal masses have been detected in the recent decades. This is why renal masses are frequently found in healthy individuals. Despite the steady case number of new malignant kidney masses from 2008 to 2016, the 5-year survival rate has improved due to advancements in detection and treatment methods.
Signs and Symptoms of Renal Mass
Renal masses, often discovered accidently during scans, usually do not have any specific signs or symptoms. There is a classic trio of symptoms – blood in the urine, discomfort in the flank area, and a mass in the flank region, which are uncommon today since renal masses are generally identified much earlier through diagnostic imaging. However, it’s not impossible to see these signs; about 15% of patients might experience them, usually when the condition is advanced, and it’s crucial for such cases to undergo further examination. Other general but important signs to watch for include new high blood pressure, unexplained weight loss, and night sweats.
Blood tests might reveal conditions like anemia, polycythemia, or hypercalcemia, which can help with the diagnosis. Doctors would carry out a physical test to look for swollen veins in the scrotum as it may indicate the spread of the renal mass.
A thorough medical history is required, which should include information on the person’s smoking habits, diet, frequency of exercise, concurrent health issues, and exposure to substances that are known to cause cancer.
It’s been suggested that obesity, high blood pressure, and smoking could be present in half of all cases. Simultaneously, people with a high body mass index, high levels of fat in the blood, or high blood sugar levels seem to have an increased risk of developing renal cell carcinoma.
Workplace exposure to dyes that contain hydrocarbons has been long believed to cause renal cell carcinoma, but recent studies are not definitive and need further investigation. Family history and concurrent diseases become essential in case they prove to be positive. For example, conditions like end-stage kidney disease have been linked to renal cell carcinoma due to a tendency for kidney cyst formation, which could lead to abnormal cell growth. Similarly, people with a familial history of genetic disorders like polycystic kidney disease are at an increased risk and need careful monitoring.
Testing for Renal Mass
Assessing a kidney mass can vary depending on the patient’s symptoms, age, or other characteristics. If you have signs like blood in your urine, a noticeable mass in your side, or pain in your side, your doctor will likely do additional tests. These can include blood tests, CT scans, MRIs, or ultrasound to get a view of your kidneys.
The choice between a CT scan and an MRI will depend on the specifics of your tumor and your health. A CT scan might be chosen if it’s important to get a picture very quickly or if you have a condition that makes MRI scans unsuitable, such as having metal implants. An MRI, on the other hand, might be preferred for a clearer picture of smaller kidney masses, without the use of radiation.
Now, just because you have a kidney mass doesn’t mean it’s cancerous. In fact, most kidney masses are not, but it’s still important to check. Certain signs on advanced imaging methods can help determine if a mass is benign (non-cancerous) or malignant (cancerous). For instance, on a CT scan, a mass with a lot of fat content is likely a benign tumor called an angiolipoma. On the contrary, a mass that strongly enhances on the scan doesn’t contain much fat and is therefore more likely to be cancerous.
If your doctor suspects your kidney mass might be renal cell carcinoma (a type of kidney cancer), they’ll want to check if the cancer has spread. This type of cancer most commonly spreads to the lung, but it can also be found in soft tissues, bones, the liver, or the brain. Advanced imaging such as CT scans of the chest and brain and a bone scan might be used to check for spread. Blood tests, including a complete blood count, liver function tests, calcium levels, and a general metabolic panel, can also be helpful in assessing your condition.
Size does matter when evaluating a kidney tumor. Generally, tumors that are 3-4 cm or smaller have less potential to be malignant. About 40% of 2 cm kidney masses are benign, and only 10% are high-grade renal cell carcinoma. But when a renal mass is 4 cm or larger, up to 30% are high-grade cancer. Therefore, larger renal masses require more thorough evaluation due to the higher chance of being cancerous.
Treatment Options for Renal Mass
The management of a kidney mass can vary greatly depending on factors like the patient’s size, the shape and pathology of the tumor, and many others. Doctors might choose to closely monitor the mass, take a biopsy (a sample of cells or tissues from the mass), remove it surgically, or use thermal ablation (heat treatment) to destroy it. The choice depends on weighing the risks and benefits, and considering things like the patient’s age, other health conditions, and risk factors.
For instance, if a patient has a short life expectancy, it might be better for them to opt for close monitoring or ablation, depending on the characteristics of the tumor. This is because it’s more likely that they could have negative results from other health conditions or surgery, rather than from the tumor itself.
A renal biopsy, or a sample removed from the kidney for examination, may be necessary when it’s difficult to identify the characteristics of the kidney mass. Although a significant number of renal biopsies (around 15%) still don’t provide a clear result and might necessitate additional biopsies. This procedure does have risks, like the formation of a hematoma (a collection of clotted blood), kidney failure, and other complications. So, it’s generally only recommended in certain situations. For example, if a patient is a candidate for surgery, a biopsy can provide valuable information that guides the treatment plan. However, it’s usually not recommended if the results won’t affect the management of the condition. For instances when the mass is less than 1 cm, a biopsy is often deemed unnecessary.
Thermal ablation might be a good option for patients who are not suitable for surgery. This procedure, which involves heating the tumor to destroy it, is typically recommended for tumors that are less than 3 cm in size. Ablations are less invasive than surgery, however, they do carry a higher risk of the cancer returning, making active surveillance and possibly more treatment necessary. A percutaneous biopsy (tissue sample taken through the skin) is often recommended to monitor the outcomes of the procedure.
Surgery is the most comprehensive intervention for malignant (cancerous) kidney masses. The two most common types are partial and radical nephrectomy (complete removal of the kidney). A partial nephrectomy is generally preferred as it preserves more of the kidney’s function, especially in patients with chronic kidney disease stage 3 or worse. However, this surgery comes with a higher risk of bleeding. A total nephrectomy might be necessary when the tumor is particularly aggressive or larger than 5cm.
In some cases, active surveillance (close monitoring without intervention) is the best course of action, especially for small, benign (harmless) tumors. When a tumor is less than 1cm and grows slowly, further imaging and biopsy usually aren’t beneficial due to the low risk of the tumor becoming malignant. These patients are often recommended for active surveillance. This is also the case for patients who aren’t suitable for surgery. For instance, an elderly patient with a short life expectancy and a tumor smaller than 4cm could be a good candidate for active surveillance. While there isn’t a standard guideline for how often active surveillance should take place, it’s generally recommended to monitor the kidney mass with ultrasound, CT, or MRI every 3 to 6 months for the first year, with the frequency adjusted based on the kidney pathology and progression.
What else can Renal Mass be?
When there’s a mass in the kidney, it’s crucial to first rule out infection and abscess because these conditions require antibiotic treatment. Once an infection is found to be not the cause, further investigations are needed to check for the possible presence of serious conditions like cancer. These could be renal cell carcinoma, metastasis, or lymphoma. Alongside this, the detection of benign tumors – those which are not usually harmful – is also vital. Examples of such are oncocytoma, angiomyolipoma, or adenoma. These typically only require monitoring and often do not need treatment.
What to expect with Renal Mass
The future health outlook for a kidney mass largely depends on the specific type of tumor identified. Renal Cell Carcinoma (RCC) is responsible for approximately 15,000 deaths a year or 80% of all kidney and renal pelvic cancers. Survival rates generally improve with early diagnosis and treatment. According to the American Cancer Society, for early stage kidney cancer (stage 1 and 2), the survival rate is over 90%. But if the cancer has spread to distant parts of the body (stage 4), the 5-year survival rate drops to about 13%. For stage 3 kidney cancer, the survival rate can be as high as 70% in patients who have their kidney removed surgically, however, if the cancer has spread to the kidney’s main blood vessels, the health outlook can be less favorable.
There are other types of kidney tumors, like classical variant angiomyolipomas, which tend to grow very slowly. A study followed 90% of tumors that were less than 1.5 cm in size over 5 years, and found they didn’t grow. However, the term “epithelioid” is used to describe a different variant of these tumors, which have a small but notable risk of becoming malignant (cancerous). In a small study of 40 people with these tumors, about 9 (26%) saw their tumors become malignant.
Another type of tumor is the oncocytoma, which is largely benign and well-organized when compared to RCC. Unlike RCC, these tumors are encapsulated and not aggressive or invasive. However, dense kidney cancer can be seen in up to 30% of patients who have oncocytomas, which means it’s important for patients with this condition to be regularly checked for kidney malignancy. In contrast, a metanephric adenoma is also largely benign. Its symptoms can resemble RCC, with patients possibly experiencing side pain, blood in urine, and a palpable mass. However, they are more common in women than men, unlike RCC tumor. Examining the tissue under a microscope is the most common way to confirm the presence of this type of tumor. As most adenomas (up to 90%) have a genetic mutation known as BRAF V600, there are no surgical procedures recommended as they are largely benign.
Possible Complications When Diagnosed with Renal Mass
Making a decision between surgery and ongoing monitoring has to balance the possible risks and benefits. For cases where surgery is required, it’s crucial to consider the risk of infection, excessive bleeding, and kidney failure. This is why patients need to be evaluated thoroughly before going through any invasive procedures. If surgery isn’t an option for the patient, ablation, or destroying the tissue, can be an alternative. Even though ablation typically has fewer complications compared to surgery, there is a higher chance of the issue returning, which could necessitate multiple rounds of treatment. It’s a must for healthcare providers to thoroughly explain the potential risks and benefits to patients before they undergo any treatments.
To summarise, the considerations before a treatment are:
- Evaluating risks and benefits of surgery versus ongoing monitoring
- Risks of infection, bleeding, and kidney failure associated with surgery
- Patient assessment prior to any invasive procedure
- Consideration of ablation, if surgery isn’t feasible
- Possible recurrence of issue and need for multiple ablation sessions
- Need for detailed patient education about risks and benefits of the treatment
Preventing Renal Mass
It’s important to make patients aware of the factors that can increase the risk of developing renal cell carcinoma, a kind of kidney cancer. These factors can include smoking, drinking alcohol, being overweight, having certain genetic conditions, exposure to environmental toxins, and undergoing dialysis. Heath advice for these patients can include quitting smoking and drinking, as well as incorporating more fruits and vegetables into their diet. These healthier choices have been linked to a reduced chance of developing kidney cancer.
In some cases, a patient’s specific medical history and kidney health will mean that doctors recommend genetic counseling. This type of support, often provided to both the patient and their family, can be useful when dealing with specific genetic conditions such as Von-Hippel Lindau disease, hereditary leiomyomatosis and renal cell cancer, Birt-Hogg-Dubé syndrome, and hereditary papillary renal carcinoma.
Workers who have been exposed to certain toxic substances, like polycyclic aromatic hydrocarbons, may need to be examined more closely. However, it’s worth noting that the research linking this kind of exposure to kidney cancer isn’t definitive. According to a study in 2011, there may be a link between the long-term use of certain types of anti-inflammatory drugs (those that don’t contain aspirin) and an increased risk of kidney cancer. However, this was the first time this kind of link has been found, and more research is needed to confirm it. Because of this, patients should always discuss the potential risks and benefits of any medication they’re taking with their doctors.
