What is Renal Lymphoma?
The kidneys can be affected by lymphoma, a type of cancer that starts in the lymph system. This is usually seen when lymphoma has spread throughout the body, which is referred to as secondary renal lymphoma (SRL). However, there are rare instances where the lymphoma only affects the kidneys and doesn’t appear anywhere else in the body. This is known as primary renal lymphoma (PRL).
Diagnosing kidney lymphoma can be tricky, but knowing what to look for in medical imaging can help differentiate it from other kidney cancers, such as renal cell carcinoma (RCC). This is essential because the types of treatment for these two conditions are different – kidney lymphoma is usually treated with chemotherapy while RCC is typically managed with surgery or ablation, which is a process that destroys cancer cells.
Secondary renal lymphoma, which occurs when the lymphoma has spread throughout the body and reached the kidneys, is fairly common in cases of late-stage systemic lymphoma. In contrast, primary renal lymphoma, where the lymphoma originates within the kidney itself, is quite rare. It accounts for only 0.7% of lymphomas that occur outside the lymph system.
What Causes Renal Lymphoma?
Kidneys can be affected by non-Hodgkin disease in 30% to 60% of cases when examining the body after death. People are more likely to be affected if they have a weakened immune system because of uncontrolled Epstein-Barr virus growth, an organ transplant, cancer treatment, HIV infection, or a disease called ataxia-telangiectasia.
However, a form of lymphoma (a type of cancer) directly affecting the kidneys, known as primary renal lymphoma, is very rare. It represents less than 1% of kidney lymphomas and typically begins in lymph nodes near the kidney or in the kidneys themselves.
The growth of this type of tumor has been found to be linked with long-term (chronic) inflammatory and infectious diseases such as Sjogren’s syndrome, systemic lupus erythematosus (a disease where your immune system attacks your own tissues and organs), chronic pyelonephritis (a type of kidney inflammation), and infections with the Epstein-Barr virus.
Risk Factors and Frequency for Renal Lymphoma
The kidneys are the organ in the abdomen that is most commonly affected by a type of cancer called non-Hodgkin lymphoma. A special type of kidney cancer, known as renal lymphoma, is quite rare, being seen primarily in the middle to elderly age groups. While autopsies of lymphoma patients show evidence of renal lymphoma in around 30% to 60% of cases, kidney involvement is only visibly detected in 5% of cases when using a CT scan for diagnosis. Out of all the lymphoma types that originate outside the lymphatic system in North America, renal lymphoma stands at about 0.7%. It’s also noted that in 10% to 20% of the cases, both kidneys are affected.
- Renal lymphoma is a condition that primarily affects older people.
- Autopsies show it in roughly 30% to 60% of lymphoma patients.
- However, CT scans only pick it up in about 5% of lymphoma patients.
- Renal lymphoma is rare, accounting for less than 1% of total cases.
- It accounts for about 0.7% of lymphomas that originate outside the lymphatic system in North America.
- In 10% to 20% of cases, both kidneys are affected.
Signs and Symptoms of Renal Lymphoma
Renal lymphoma, which affects the kidneys, is often part of wider systemic issues, but occasionally, it can develop as a primary disease. This condition usually shows up in middle-aged people, but sometimes, it doesn’t cause any noticeable symptoms. If symptoms do happen, they can include discomfort on the side of the body (flank pain), unexplained weight loss, fever, night sweats, feeling a lump in your abdomen, blood in your urine, and a spike in creatinine levels which indicates impaired kidney function.
Although renal lymphoma is a disease where the tumor grows in a way that it does not disturb the organ’s normal structure or function, its most common telling signs include acute kidney failure, flank pain, and a palpable mass. The precise reason behind kidney failure in this case is not clear, but experts have several assumptions including the spreading of the lymphoma into the kidney tissue, an excess of vitamin D produced by the lymphoma leading to high calcium levels, or pressure on the kidney’s blood vessels or tubules due to the tumor itself.
- Discomfort on the side of the body (flank pain)
- Unexplained weight loss
- Fever
- Night sweats
- An abdominal lump you can feel
- Blood in urine
- Increase in creatinine levels (poor kidney function)
- Acute kidney failure
Testing for Renal Lymphoma
When it comes to studying kidney function, blood tests are crucial. The tests you may be asked to go through include blood urea nitrogen (BUN) and creatinine tests. These can help find concerning signs of medical conditions, for example, lymphoma. Lymphoma has only been found to affect the kidneys clinically in 2% to 14 % of patients. However, an increased serum creatinine, an indicator for kidney function, has been reported in 26% to 56% of patients. High levels of BUN or creatinine can show blockage in both ureters, the tubes which drain urine from kidneys to the bladder, due to oversized lymph nodes in the area surrounding the spine or can be seen as a side effect after receiving chemotherapeutic drugs that can harm the kidneys.
If your doctor suspects you have primary renal lymphoma (a form of lymphoma that starts in the kidneys), you will most likely need a biopsy. This is where a small sample of cells or tissues are removed from your body for laboratory testing. Though there are various techniques available, core tissue biopsy is usually recommended. This procedure helps analyze the tissue cells more accurately to provide a confirmatory diagnosis. It’s worth noting that if the lymphoma has already spread to other parts of your body, a kidney biopsy may not be needed.
Imaging tests like CT scans play an important role in understanding how the lymphoma might affect your kidneys. You may come across multiple nodular masses of variable sizes within the kidneys – this is a common finding and is seen in 50 to 60% of lymphoma cases. Moreover, these lesions are usually present in both kidneys, although they may only affect one kidney. Another common finding is the lymphoma spreading to the kidneys or the area around the kidneys from large lymph nodes in the back of the abdomen – seen in 25% to 30% of cases.
Kidney lymphoma may appear as a single mass in 10% to 25% of the cases. CT scans can help differentiate kidney lymphoma from kidney cancer, a type of cancer that mostly shows more uptake of contrast material. In addition to this, nuclear imaging can also be utilized for diagnosis and tracking the lymphoma’s progress. This includes the use of certain types of radioactive substances that are taken up by lymphoma tissue in the kidneys, helping to detect its presence more effectively.
Treatment Options for Renal Lymphoma
Distinguishing kidney lymphoma from other kidney tumors is very important, but can also be very difficult. This is especially the case when the lymphoma appears similar to kidney cancer in scans and tests. Usually, when a patient has a kidney tumor, doctors will remove part or all of the kidney. However, for kidney lymphoma, the usual treatment is systemic chemotherapy, which uses drugs that travel through the whole body.
For individuals who have lymphoma in the kidney, there are two common treatments available: surgery and systemic chemotherapy. This last one involves drugs that can be combined with, or without, radiation therapy. Even though these treatments are efficient, it’s important to know that prognosis, or the likely course or outcome of the disease, for people with primary kidney lymphoma can be quite serious, regardless of whether the disease has spread or not.
For cases where both kidneys are involved, doctors usually recommend a specific chemotherapy regimen, composed of several drugs (cyclophosphamide, doxorubicin, vincristine, and prednisone), as the preferred method of treatment. Chemotherapy typically helps improve kidney function, but the long-term outlook can be poor. This is because, even though chemotherapy usually improves kidney function, the existing reports indicate that the death rate is high due to either fast disease recurrence or infections resulting from low neutrophil counts, a condition known as neutropenia.
Alternatively, removing both kidneys, an option known as bilateral nephrectomy, will unavoidably lead to the patient needing permanent artificial kidney cleaning procedures or hemodialysis. Though the survival rates and long-term periods without the disease are better when surgery and chemotherapy are done together.
What else can Renal Lymphoma be?
Here are some medical conditions that a doctor may consider when diagnosing a patient:
- Abscess
- Acute pyelonephritis (sudden and severe kidney infection)
- Angiomyolipoma (a benign tumor in the kidney)
- Bladder cancer
- Chronic pyelonephritis (long-term kidney infection)
- Non-Hodgkin lymphoma (cancer that starts in cells called lymphocytes, part of the body’s immune system)
- Renal adenoma (small, benign kidney tumor)
- Renal cyst (fluid-filled mass in the kidney)
- Renal infarction (obstruction of blood flow to the kidneys)
- Wilms disease (a rare kidney cancer that primarily affects children)
