Wilms Tumor- Stages and Different Types of Wilms Tumor

Wilms tumor is a rare type of kidney cancer that is commonly diagnosed in children. It accounts for about 6-7% of childhood cancers. There are different types of Wilms tumors based on their aggressiveness and the cell type that they arise from.

Gaining an understanding of the crucial aspects of Wilms tumor, such as its types, stages, risk factors, and treatment options, will support informed decision-making among patients and help them lead a healthy life.

What is Wilms Tumor?

Wilms tumor, also known as nephroblastoma, Wilms cancer, or Wilms nephroblastoma, is a rare form of kidney cancer that primarily affects children.

Nephroblastoma usually arises from immature kidney cells. The immature cells present during the early development of the fetus are destined to mature and develop into the glomeruli and nephrons, which are responsible for filtration. When these cells fail to mature, they can form clumps at birth. By age 3 or 4, these clumps might begin to grow uncontrollably to form Wilms tumor.

How Common is Wilms Tumor?

Wilms tumor, or Wilms cancer, is one of the most common types of kidney cancer in children. It represents approximately 6-7% of all childhood cancers. The incidence is higher in certain age groups, peaking between 3 and 4 years old. Although relatively rare, the recognition of Wilms nephroblastoma is vital due to the potential for successful treatment and positive outcomes.

What are the Most Common Types of Wilms Tumor?

There are different types of Wilms tumor depending on the cell type from which they arise. Certain types of Wilms have a better prognosis than others. Based on the histology, the following are the different types of Wilms tumor:

Favorable Histology

This is the more common and less aggressive form of Wilms tumor. The cells in favorable histology tumors appear normal under the microscope, and the prognosis is generally favorable with appropriate treatment.

Anaplastic Histology

This is also referred to as an unfavorable Wilms tumor. Anaplastic histology represents a more aggressive subtype of Wilms cancer. The cells in these tumors exhibit abnormal features under the microscope, and treatment approaches may need to be more intensive to address the increased risk.

Other Types of Kidney Cancer Found in Children

While Wilms tumor is the predominant kidney cancer in children, other types include:

Mesoblastic Nephroma

A rare tumor occurring in early infancy, mesoblastic nephroma is usually benign but can occasionally be malignant.

Clear Cell Sarcoma of Kidney (CCSK)

Clear cell sarcoma of the kidney is a rare and aggressive kidney cancer that typically affects children.

Malignant Rhabdoid Tumor of the Kidney

This is a rare and aggressive tumor that occurs in young children. It is characterized by the loss of a specific gene, resulting in rapid tumor growth.

Renal Cell Carcinoma

While more common in adults, renal cell carcinoma can occur in children. It is distinct from Wilms tumor in terms of its biology and treatment approach.

What are the Stages of Wilms Tumor?

Childhood kidney cancer, or Wilms tumor, is classified into stages to determine the extent of its spread. Wilms tumor staging helps guide treatment decisions and predict prognosis. The stages range from localized tumors confined to the kidney to more advanced cases with widespread involvement. The following are the different stages of Wilms cancer:

Stage 1 Wilms Tumor

In this initial stage, the tumor is limited to the kidney and can often be completely removed through surgery. The prognosis for Stage 1 Wilms tumor is generally favorable, with high chances of successful treatment.

Stage 2 Wilms Tumor

Stage 2 involves a nephroblastoma that extends beyond the kidney but is still completely removable by surgery. Despite the tumor's extension, the prognosis remains favorable, and treatment success is achievable with comprehensive therapeutic approaches.

Stage 3 Wilms Tumor

At this stage, the tumor has spread beyond the kidney and may involve nearby structures or lymph nodes.

Stage 4 Wilms Tumor

Stage 4 signifies a more advanced stage where the tumor has spread to distant organs or lymph nodes. Treatment for stage 4 Wilms tumor demands a comprehensive treatment approach to target both the primary tumor and distant metastases.

Stage 5 Wilms Tumor

The final stage, stage 5, indicates bilateral involvement, where tumors are present in both kidneys. Managing stage 5 Wilms tumor is complex, requiring a multidisciplinary approach to address tumors in both kidneys and any potential spread.


Understanding the stages of nephroblastoma is crucial for tailoring effective treatment plans. Prognosis varies based on the extent of tumor spread, with early-stage tumors often having more favorable outcomes. A collaborative effort between patients, uro-oncologists, pediatric oncologists, and families is essential for navigating the challenges associated with each stage and achieving the best possible outcome for children diagnosed with Wilms cancer.

Frequently Asked Questions

The survival rate for Wilms tumor is generally high, with approximately 9 out of 10 children diagnosed surviving the disease. Early detection, advances in treatment modalities, and a multidisciplinary approach contribute to the positive prognosis. However, individual outcomes may vary, and factors such as the tumor stage and response to treatment influence survival rates.

Wilms tumor and nephroblastoma are terms used interchangeably to refer to the same kidney cancer predominantly affecting children. Both describe embryonal kidney cancer characterized by the abnormal growth of kidney cells. "Nephroblastoma" is a more technical term, while "Wilms tumor" is commonly used in clinical settings.

Wilms tumor doesn't have a specific color. It is a mass of abnormal kidney cells that typically appears as a solid lump. The coloration can vary, often depending on the composition of cells and blood vessels within the tumor. During medical examinations, nephroblastomas are visualized through imaging techniques like ultrasound, CT scans, or MRIs rather than by color.

Wilms tumor itself may not always cause pain, especially in the early stages. However, if the tumor grows large enough, it can lead to discomfort or pain in the abdomen. Additionally, if the tumor compresses nearby structures or nerves, it may cause pain.

The "Rule of 10" in Wilms tumor refers to a guideline used in Wilms tumor diagnosis. According to this rule, about 10% have unfavorable features, are bilateral, involve blood vessels, show calcifications on scans, or have spread to the lungs at diagnosis. However, each Wilms tumor is unique, and individual factors determine treatment and prognosis.