Neuroblastoma vs Wilms Tumor: The Difference, When Each Is Used and How to Decide

It usually starts at bath time. A parent runs a washcloth over a toddler’s belly and feels something that was not there last week: a firmness under the ribs, or a swelling on one side that does not move the way a full bladder or a gassy tummy does. The child, more often than not, is playing happily. That mismatch, a calm child and a worried hand, is how many pediatric abdominal tumors are first found.

From that moment, two names tend to come up quickly in the clinic. One is neuroblastoma. The other is Wilms tumor. To a frightened family they can sound interchangeable: both are rare, both strike young children, both show up as a mass in the same part of the body. Yet they behave so differently that pediatric oncologists treat the distinction as the first real fork in the road.

This article walks through how that fork is navigated, what the evidence actually says about outcomes, and which questions deserve honest answers rather than reassurance.

Why do two very different cancers get confused for each other?

The confusion is anatomical before it is medical. The adrenal gland sits like a small cap directly on top of each kidney. A tumor growing from the adrenal gland and a tumor growing from the kidney beneath it occupy almost the same real estate in a small child’s abdomen. On a physical exam, and sometimes on a first ultrasound, they can look like the same problem: a solid mass in the flank, pushing the belly outward.

Timing adds to the overlap. Both cancers are overwhelmingly diseases of the first five years of life. Neuroblastoma is the most common cancer diagnosed in babies under one year old, and about 90 percent of cases are found by age five, according to the National Cancer Institute. Wilms tumor most often appears in children around three to four years of age, per Mayo Clinic. A pediatrician feeling a mass in a two-year-old is therefore standing squarely in the territory of both.

The similarities largely stop there. Neuroblastoma arises from primitive nerve cells that belong to the sympathetic nervous system, the same network that controls the fight-or-flight response. Wilms tumor arises from leftover embryonic kidney tissue that never finished developing. Different origins mean different behavior, different spread patterns, different laboratory signals and, ultimately, different treatment paths.

The title question of this article, when each diagnosis is used and how to decide, is really a question about how a care team narrows those two possibilities down to one. That process is more orderly than most families expect.

Neuroblastoma vs Wilms tumor at a glance

A side-by-side view helps because the differences are not subtle once they are lined up. The table below summarizes the features clinicians weigh most heavily, drawn from mainstream references cited at the end of this article.

Feature	Neuroblastoma	Wilms tumor
Tissue of origin	Immature sympathetic nerve cells; most often the adrenal gland	Kidney (embryonic kidney tissue)
Typical age	Infants and toddlers; median age about 17 months	Peak around ages 3 to 4
Relationship to the midline	Often crosses the midline of the abdomen	Usually stays on one side
Behavior toward blood vessels	Tends to wrap around and encase the aorta and its branches	Tends to push vessels aside
Relationship to the kidney	Displaces the kidney downward and outward	Arises within it; normal kidney tissue seems to claw around the mass
Urine chemistry	Breakdown products of adrenaline-type hormones often elevated	Normal; blood in urine possible
How the child looks	Frequently unwell: pain, fever, irritability, weight loss	Frequently well apart from the mass
Common spread at diagnosis	Bone, bone marrow, liver, lymph nodes	Lungs, sometimes liver

No single row is decisive on its own. A young, unwell child with a mass that hugs the aorta and abnormal urine chemistry points strongly toward neuroblastoma. A cheerful three-year-old with a smooth, one-sided mass and clear urine chemistry points toward Wilms. Real children do not always read the textbook, which is why the final word belongs to the pathologist, not the radiologist or the pediatrician.

Where does each tumor actually come from?

Neuroblastoma is a cancer of development that went slightly wrong. Early in fetal life, a population of cells called the neural crest migrates through the embryo to form the sympathetic nervous system and the inner core of the adrenal glands. Some of those cells are supposed to mature into nerve cells; others are supposed to disappear. Neuroblastoma arises when a group of these immature cells keeps dividing instead. Because sympathetic tissue runs in a chain along the spine from neck to pelvis, neuroblastoma can begin almost anywhere along that route. The adrenal gland is the most common site, but the neck, chest and pelvis are all possible, as the NHS and Mayo Clinic both describe.

Wilms tumor has an equally embryonic story, only in a different organ. The kidney forms from tissue that is supposed to be fully used up by the time a baby is born. In some children, small clusters of this primitive kidney tissue persist. Most never cause trouble, but occasionally one begins to grow uncontrolled and becomes a Wilms tumor. This is why Wilms is sometimes called nephroblastoma, literally a tumor of kidney-forming cells.

The distinction matters clinically. Sympathetic nerve cells manufacture adrenaline-family chemicals, so neuroblastoma often leaves a chemical fingerprint in the urine. Kidney cells do not. Neural tissue is also intimately wrapped around the great blood vessels of the abdomen, which explains neuroblastoma’s habit of encasing them. Kidney tissue sits off to one side, which explains why Wilms tends to displace rather than surround.

Which age group does each cancer affect?

Age is the first clue a clinician registers, sometimes before the child is even on the examination table. Neuroblastoma skews very young. The National Cancer Institute reports a median age at diagnosis of about 17 months, and notes that it is the most common cancer in infants under one year. Cases in children over ten are unusual.

Wilms tumor sits a little later on the timeline. Mayo Clinic describes it as most common in children ages three to four, becoming much less common after age five. Cases in infants do occur, and so do cases in older children and adolescents, but the center of gravity is the preschool years.

The overlap in the one-to-three-year window is exactly where the differential diagnosis becomes hardest, and where the other clues, imaging, urine chemistry and the child’s general condition, carry more weight.

Age also shapes prognosis in a way that is almost unique to neuroblastoma. Infants with neuroblastoma, even with disease that has spread to the liver or skin, frequently do far better than older children with an equivalent burden of disease, according to the NCI. Some infant tumors regress on their own without any treatment at all, a phenomenon that has few parallels elsewhere in oncology. Age at diagnosis is therefore built directly into the risk-grouping systems used to plan neuroblastoma care.

Wilms tumor outcomes are less age-dependent. What matters more is the stage at diagnosis and the microscopic appearance of the tumor cells, which pathologists classify as favorable or unfavorable histology.

Does neuroblastoma or Wilms cross the midline?

This is one of the most searched questions about the two cancers, and it comes from a real clinical rule of thumb. Neuroblastoma tends to cross the midline of the abdomen. Wilms tumor tends to stay on its own side.

The reason goes back to anatomy. Sympathetic nerve tissue lies along the spine in the very center of the body, directly in front of the vertebrae and alongside the aorta. A tumor growing from that tissue is already sitting on the midline; growth in any direction can carry it across. Neuroblastoma also has a tendency to grow around structures rather than push them away. On a CT or MRI scan, radiologists often see the aorta and its branches passing straight through the mass, encased rather than displaced. That encasement is a classic neuroblastoma sign and a major reason these tumors can be difficult to remove surgically.

Wilms tumor begins inside the kidney, which sits off to one side of the spine. As it grows it expands the kidney and compresses neighboring organs, but it usually respects the midline and pushes blood vessels aside rather than swallowing them. Radiologists describe a claw sign, where a rim of normal kidney tissue appears to grip the edge of the mass, confirming that the tumor arose from within the kidney rather than beside it.

Rules of thumb are not laws. Very large Wilms tumors can extend past the midline, and a small neuroblastoma may not. Wilms tumor can also grow into the renal vein and up toward the heart, which is a different kind of vascular involvement from neuroblastoma’s encasement. The midline question is a helpful early signal, weighed alongside everything else.

How do the symptoms differ in a child?

Ask an experienced pediatric nurse to describe a typical child with each cancer and you will hear two different stories.

The child with Wilms tumor is often surprisingly well. A parent or caregiver notices a swollen belly or feels a firm, smooth lump on one side, frequently during a bath or diaper change. The child may have no other complaints. Mayo Clinic lists possible accompanying signs such as abdominal pain, fever, blood in the urine, high blood pressure, nausea and loss of appetite, but the painless mass in an otherwise thriving preschooler is the classic picture.

The child with neuroblastoma, particularly one whose disease has already spread, is more likely to look and act sick. The NHS and Mayo Clinic describe a wider and more varied list: a swollen, painful abdomen; bone pain that can make a toddler limp or refuse to walk; tiredness, pallor and unexplained fever from bone marrow involvement; weight loss; and irritability. Two signs are almost unique to neuroblastoma. One is bruising or dark discoloration around the eyes, sometimes with bulging, caused by tumor spread to the bones of the eye socket. The other is a rare neurological syndrome of jerky eye movements and unsteady limbs, thought to be triggered by the immune system’s reaction to the tumor.

Neuroblastoma in the chest or neck can produce a droopy eyelid and a smaller pupil on one side, from pressure on sympathetic nerves. Tumors growing near the spine can press on the spinal cord, causing weakness or difficulty with bladder and bowel control.

None of these signs is proof. Many children with neuroblastoma present with nothing more than a lump, and some children with Wilms feel unwell. Symptoms tilt the balance; tests settle it.

Which tests tell neuroblastoma and Wilms tumor apart?

The work-up follows a fairly consistent sequence, described in patient guides from the NCI, Mayo Clinic and the NHS.

Ultrasound usually comes first because it is painless, quick and involves no radiation. It confirms that the lump is a solid mass rather than fluid, shows which organ it appears to come from and can check whether it has grown into the renal vein.

Cross-sectional imaging follows, with CT or MRI. This is where the midline behavior, vessel encasement versus displacement, and the claw sign become visible. Calcium deposits inside the mass are more typical of neuroblastoma than Wilms, and radiologists note their presence as one more piece of the puzzle. MRI is increasingly used in children to reduce radiation exposure, and specialized MRI sequences that measure how freely water molecules move within tissue are being studied as a way to separate the two tumors, although this remains a research area rather than a settled standard.

Urine testing is one of the sharpest tools. Neuroblastoma cells often make excess adrenaline-family hormones, and the breakdown products of those hormones spill into the urine. A simple urine collection showing elevated levels points strongly toward neuroblastoma, and the NCI notes these markers are also used to track response over time. Wilms tumor does not produce them.

Blood tests assess kidney function, blood counts and general health. In suspected neuroblastoma, a bone marrow sample and a specialized nuclear medicine scan that homes in on sympathetic nerve tissue are used to look for spread, per the NCI. In suspected Wilms, a chest CT checks the lungs, the most common site of spread.

Biopsy, or in some Wilms cases removal of the whole kidney followed by pathology, gives the definitive answer. Under the microscope the two tumors look nothing alike, and molecular testing of tumor tissue further refines the risk group.

Can neuroblastoma be mistaken for Wilms tumor?

Yes, and the reverse is possible too. Several of the top medical search results for this topic are case reports of a rare situation: neuroblastoma arising inside the kidney itself. Sympathetic nerve tissue can be found within or immediately beside the kidney, and on rare occasions a neuroblastoma grows there. On imaging it can show the claw sign and stay on one side, looking for all the world like Wilms tumor. Only the pathologist’s examination of the tissue reveals the truth.

This is not an academic curiosity. In some parts of the world, notably in European treatment protocols, children with a classic imaging picture of Wilms tumor may begin chemotherapy before surgery, without a biopsy, because the diagnosis is considered sufficiently certain. The medications chosen for Wilms are not the medications chosen for neuroblastoma. A misread scan could therefore lead to weeks of the wrong treatment. Clinicians guard against this by paying attention to red flags that do not fit: abnormal urine chemistry, calcification, vessel encasement, a very young or very unwell child. When something does not add up, a biopsy is obtained first.

A large Wilms tumor can also be mistaken for neuroblastoma when it grows past the midline or when it is hard to tell which organ it came from. Here too, urine testing is a quick tiebreaker.

The lesson for families is that a first impression from a scan is exactly that, a first impression. Care teams expect it to be revised, and the pause between imaging and confirmed diagnosis, while agonizing, is time spent getting the answer right.

When is each diagnosis used, and how do doctors decide?

The phrase in this article’s title, when each is used, deserves an honest translation. Nobody chooses to use a diagnosis. What clinicians do is assign a working diagnosis based on probability, then confirm or overturn it with evidence.

The working diagnosis of neuroblastoma is favored when the child is very young, especially under two; when the mass appears to sit above or beside the kidney rather than within it; when it crosses the midline or wraps around the aorta; when calcium deposits are visible; when urine hormone breakdown products are elevated; and when there are signs of spread to bone or bone marrow, such as bone pain, limping, anemia or bruising around the eyes.

The working diagnosis of Wilms tumor is favored when the child is a preschooler around three or four; when imaging shows the mass arising from within the kidney with a claw of normal tissue around it; when the tumor pushes vessels aside rather than surrounding them; when urine chemistry is normal; when there is blood in the urine; and when the child is otherwise well. A history of certain congenital conditions raises suspicion further. The NCI and Mayo Clinic note that children with an absent iris, overgrowth of one side of the body, urinary or genital malformations, or certain named syndromes carry a higher risk of Wilms and are often screened with regular ultrasound.

Confirmation comes from tissue. Once the diagnosis is secure, the work of staging begins. For Wilms, stage is largely defined by how far the tumor extends and whether it was completely removed. For neuroblastoma, an international system combines imaging-defined risk factors with age, tumor genetics and microscopic appearance to sort children into low, intermediate or high-risk groups, according to the NCI. That risk group, more than the diagnosis alone, determines what happens next.

How does treatment differ between the two cancers?

Treatment is where the two paths diverge most sharply, and where the risk group matters as much as the name of the disease. Specific medicines and regimens are decisions for the child’s oncology team; what follows describes the general shape of care as outlined by the NCI, NHS and Mayo Clinic.

Wilms tumor treatment is comparatively standardized. Surgery to remove the affected kidney and the tumor is central. In North America this is usually done first; in many European protocols, chemotherapy is given for a few weeks beforehand to shrink the tumor and make surgery safer. Chemotherapy follows surgery for most children, and radiation is added for higher stages or unfavorable microscopic features. When both kidneys are affected, which the NCI notes occurs in a small minority of children, surgeons aim to remove tumor while preserving as much working kidney as possible.

Neuroblastoma treatment ranges from almost nothing to among the most intensive regimens in pediatric oncology. Some infants with low-risk disease are simply observed, because their tumors can shrink and disappear on their own. Others need surgery alone. Intermediate-risk children typically receive chemotherapy and surgery. High-risk neuroblastoma is treated with a multi-phase plan: induction chemotherapy to shrink the disease, surgery, very high-dose chemotherapy followed by rescue with the child’s own previously collected stem cells, radiation to the tumor bed, and finally a maintenance phase that includes antibody-based immunotherapy directed against a molecule found on neuroblastoma cells, combined with medication that encourages remaining cancer cells to mature. Each phase has a distinct purpose, and the whole course commonly stretches well beyond a year.

The contrast is instructive. Two lumps in the same part of a child’s abdomen can lead to a single operation and a few months of treatment, or to a year and a half of the most demanding therapy medicine offers.

Is neuroblastoma the deadliest childhood cancer?

Not by total numbers, but the question is not unreasonable. Neuroblastoma accounts for a disproportionate share of childhood cancer deaths relative to how often it occurs. The National Cancer Institute reports that neuroblastoma is responsible for about 15 percent of all cancer deaths in children, despite making up a far smaller fraction of diagnoses. Brain and spinal cord tumors, taken together, cause more childhood cancer deaths overall.

The reason neuroblastoma weighs so heavily is its split personality. The same disease that vanishes on its own in some infants is, in its high-risk form, aggressive and prone to returning after treatment. The NCI describes five-year survival for children with high-risk neuroblastoma at roughly 50 percent, even with the intensive multi-phase treatment described above. Because high-risk disease is common among children diagnosed after infancy, this group drives the mortality figures.

Low- and intermediate-risk neuroblastoma tell a very different story, with the large majority of children surviving long term, according to the NCI. Averaging these groups together produces an overall figure that hides both the excellent and the difficult ends of the spectrum.

Wilms tumor, by contrast, is one of the success stories of pediatric oncology. The NHS states that around 9 in 10 children treated for Wilms tumor are alive and well long term. Outcomes are lower for children with unfavorable histology or disease that has spread, but even these groups fare better than high-risk neuroblastoma.

Deadliest is an unhelpful word for families, because it flattens exactly the distinctions that determine an individual child’s outlook. The more useful question is: which risk group, and what does the evidence show for that group?

Can a child survive stage 4 neuroblastoma?

Yes. Many do. The figure that matters, from the National Cancer Institute, is that about half of children with high-risk neuroblastoma, which includes most stage 4 disease in children older than infancy, are alive five years after diagnosis. That is a hard number to hear, and it is also a number that has risen steadily over recent decades as treatment has intensified and antibody-based immunotherapy has been added to the maintenance phase of care.

Stage 4 does not mean the same thing for every child. Infants with a particular pattern of spread, historically called stage 4S and now labeled stage MS, have disease in the liver, skin or limited bone marrow but no spread to bone. The NCI notes that these babies often do extremely well, sometimes with minimal treatment, because their tumors tend to mature or regress spontaneously. A parent who hears stage 4 for an infant may be facing a very different situation from a parent who hears it for a four-year-old.

Tumor biology adds another layer. Amplification of a particular growth-promoting gene, certain chromosome changes and the microscopic maturity of the cells all influence outlook independently of stage. Two children with the same stage can be assigned different risk groups and different treatment plans.

What the evidence does not support is any promise. Survival statistics describe groups of children treated in the past, not the future of the child in front of you. They are most useful as a frame for conversations with the oncology team, who can explain which group a particular child falls into and why.

Why are so many kids getting neuroblastoma?

This question surfaces often online, usually after a fundraising campaign or a viral story about a child’s diagnosis. The honest answer is that neuroblastoma remains rare and there is no mainstream evidence of a surge.

The National Cancer Institute estimates roughly 650 new cases in the United States each year. The NHS puts the UK figure at around 100 children annually. These numbers have been broadly stable over time in the surveillance data both organizations draw on. What has changed is visibility. Social media allows a single family’s story to reach millions, charity awareness days are more prominent, and pediatric cancer research now receives more public attention than it did a generation ago. A rare disease seen repeatedly on a screen begins to feel common.

Awareness of causes is more limited than families would like. Neuroblastoma is not linked to anything parents did or did not do. It originates in cells that go awry before birth, and in the vast majority of cases no cause can be identified, as Mayo Clinic and the NHS both state. A small proportion runs in families through inherited gene changes, and children with certain rare developmental conditions have higher risk. No environmental exposure, diet, infection or lifestyle factor has been convincingly tied to it in mainstream evidence.

The same holds for Wilms tumor. Most cases arise without an identifiable cause. A minority are linked to congenital syndromes or gene changes, which is why children with those conditions are offered surveillance ultrasound. Parents searching for something they missed almost never find it, because in most cases there was nothing to find.

When should a child see a doctor about a belly lump or swelling?

Promptly. Any firm lump or unexplained swelling in a child’s abdomen deserves an in-person examination, ideally within days rather than weeks. The good news is that most childhood abdominal swelling turns out to be constipation, gas, an enlarged spleen from a viral illness or simply a toddler’s naturally round tummy. The reason not to wait is that when a mass is a tumor, earlier staging tends to mean simpler treatment.

Red-flag signs that warrant same-day or emergency assessment include a child who is pale, lethargic and difficult to rouse; unexplained bruising, especially around the eyes; sudden weakness or loss of feeling in the legs, or new trouble with bladder or bowel control, which can signal pressure on the spinal cord; difficulty breathing; blood in the urine; a rapidly enlarging abdomen; and persistent bone pain or a limp with no injury to explain it. Fever together with a lump should also be seen urgently.

Seek a routine but prompt appointment for a lump without those features, for a child who has stopped eating well or is losing weight, for a preschooler with new high blood pressure discovered at a check-up, or for jerky eye movements and unsteadiness that appear over days.

Children with known risk conditions, such as an absent iris, overgrowth of one side of the body, or a family history of either cancer, should already be under a surveillance plan. If they are not, ask their pediatrician about one. Regular ultrasound in these children is standard practice according to the NCI, and it exists precisely because catching a tumor while it is small changes what treatment looks like.

What matters most when comparing neuroblastoma and Wilms tumor

Having watched families move through this territory, one observation stands out: the name of the disease matters less than most people assume, and the risk group matters more.

A parent who has just heard the word neuroblastoma may reach for the grimmest statistics. A parent who has heard Wilms tumor may feel a wave of relief. Both reactions are understandable, and both can mislead. An infant with low-risk neuroblastoma may need only watchful waiting. A child with Wilms tumor that has unfavorable microscopic features and has spread to the lungs faces a genuinely difficult course. The label opens the conversation; the details determine it.

Three things deserve a family’s attention early. First, insist on understanding the risk group or stage, not just the diagnosis, and ask what the evidence shows for children in that specific group. Second, ask whether the child is eligible for a clinical trial. Most children with these cancers in high-income countries are treated within cooperative group studies, and the steady improvement in high-risk neuroblastoma survival described by the NCI is a direct product of that approach. Third, ask about long-term follow-up from the start. Survivors of both cancers may face late effects, from kidney health after nephrectomy to hearing, heart and growth concerns after intensive neuroblastoma therapy, and structured survivorship care is part of good treatment.

The distinction between these two cancers is a triumph of careful medicine: a lump that once meant a single frightening word is now sorted, staged and treated with remarkable precision. Honesty about the difficult end of the spectrum does not take away from that. It is what allows families to place their trust in the process, and their questions in the right hands.

Frequently asked questions

What is the main difference between neuroblastoma and Wilms tumor?

Neuroblastoma starts in immature nerve cells, most often in the adrenal gland above the kidney, while Wilms tumor starts in the kidney itself. That difference in origin explains almost everything else: neuroblastoma tends to affect younger children, cross the midline, wrap around blood vessels and leave hormone breakdown products in the urine, whereas Wilms tumor usually stays one-sided, pushes vessels aside and leaves urine chemistry normal.

Does neuroblastoma or Wilms cross the midline?

Neuroblastoma is the one that typically crosses the midline. It grows from sympathetic nerve tissue that lies along the spine in the center of the body, so it is already positioned to extend across, and it tends to surround the aorta rather than push it away. Wilms tumor begins within the kidney off to one side and usually stays there, although very large Wilms tumors can occasionally extend past the midline.

Is neuroblastoma the deadliest childhood cancer?

No, brain and spinal cord tumors cause more childhood cancer deaths overall. Neuroblastoma is, however, responsible for a disproportionate share, about 15 percent of pediatric cancer deaths according to the National Cancer Institute, because its high-risk form is aggressive and prone to relapse. Low- and intermediate-risk neuroblastoma have very good outcomes, so the disease as a whole spans a wide range.

Can a child survive stage 4 neuroblastoma?

Yes, many children do. The National Cancer Institute reports five-year survival of roughly 50 percent for high-risk neuroblastoma, which includes most stage 4 cases in children older than infancy, and that figure has improved over recent decades. Infants with the special stage MS pattern often do extremely well. Statistics describe groups treated in the past, not any individual child’s future, so the oncology team is the right source for a specific outlook.

Why are so many kids getting neuroblastoma?

They are not, as far as mainstream evidence shows. Neuroblastoma remains rare, with roughly 650 new cases a year in the United States and around 100 in the UK, figures that have been broadly stable. The sense that it is rising comes from greater visibility through social media, fundraising campaigns and news coverage. Its cause is unknown in most cases and it is not linked to anything parents did.

Which is more common, neuroblastoma or Wilms tumor?

Neuroblastoma is somewhat more common. The National Cancer Institute estimates about 650 new US cases of neuroblastoma each year, compared with roughly 500 to 600 new cases of Wilms tumor. In the UK, the NHS reports around 100 children a year diagnosed with neuroblastoma and about 80 with Wilms tumor. Both remain rare diseases, and both are diagnosed overwhelmingly in children under five.

What symptoms point toward neuroblastoma rather than Wilms tumor?

A child who looks unwell tilts the picture toward neuroblastoma. Bone pain, limping without injury, pallor and tiredness, fever, weight loss, bruising or dark discoloration around the eyes, and a droopy eyelid on one side are all more typical of neuroblastoma, often because it has spread to bone or bone marrow. A well child with a smooth painless mass and possibly blood in the urine is more typical of Wilms tumor.

Can a urine test tell the two apart?

Often, yes. Neuroblastoma cells frequently produce excess adrenaline-family hormones, and their breakdown products can be measured in a urine sample. Elevated levels strongly suggest neuroblastoma; Wilms tumor does not raise them. The test is not perfect, since a minority of neuroblastomas do not release detectable amounts, so a normal result does not rule it out. Imaging and tissue examination remain the definitive steps.

Is a biopsy always needed to diagnose Wilms tumor?

Not always. In some treatment approaches, especially European protocols, a child with a classic imaging picture of Wilms tumor may begin chemotherapy before surgery without a biopsy, and the diagnosis is confirmed when the kidney is removed. In North America, upfront surgery usually provides the tissue directly. When features do not fit, such as abnormal urine chemistry or vessel encasement, a biopsy is obtained first to avoid treating the wrong disease.

Which children are at higher risk of Wilms tumor?

Most children with Wilms tumor have no identifiable risk factor. A minority have congenital conditions linked to it, including an absent iris, overgrowth of one side of the body, certain urinary or genital malformations, and specific inherited syndromes described by the NCI and Mayo Clinic. Children with these conditions are typically offered regular ultrasound surveillance so that any tumor is found while it is small and easier to treat.

This article is for general information only and is not a substitute for professional medical advice. Please consult a qualified doctor about your individual situation.