Neuroblastoma and nephroblastoma are distinct childhood cancers. While both can present as abdominal masses, understanding their specific characteristics is helpful for accurate diagnosis and tailored treatment. This article clarifies the differences between these two conditions, covering their origins, typical presentations, and management.
Understanding Neuroblastoma
Neuroblastoma arises from immature nerve cells, known as neuroblasts, which are part of the sympathetic nervous system. These cells are found throughout the body, but neuroblastoma commonly develops in the adrenal glands, located atop the kidneys, or in nerve tissue alongside the spinal cord in the abdomen, chest, or neck. This cancer is predominantly diagnosed in infants and young children, with most cases occurring before age five, and approximately one-third diagnosed by their first birthday.
Symptoms of neuroblastoma can vary widely depending on the tumor’s location and whether it has spread. Common signs parents might notice include a lump or swelling in the abdomen, neck, or chest. Other symptoms can include bone pain, fever, fatigue, pale skin due to anemia, or changes in bowel habits like diarrhea or constipation. In some infants, blue or purple lumps may appear just under the skin, or they might develop bulging eyes or dark circles around them.
Understanding Nephroblastoma
Nephroblastoma, also widely known as Wilms tumor, is a cancer that originates from immature kidney cells. This tumor typically develops in one kidney, though in about 5-10% of cases, it can affect both kidneys simultaneously. It is the most common kidney cancer in children and generally affects children between one and five years old, with an average age of diagnosis around two to three years.
The signs of nephroblastoma can also vary, but a noticeable mass or swelling in the abdomen is a common presenting symptom, often without pain. Other symptoms may include abdominal pain, fever, or blood in the urine, which occurs in about 20% of cases. Children might also experience high blood pressure, fatigue, or a loss of appetite.
Key Differences and Similarities
Neuroblastoma and nephroblastoma are both embryonal tumors, arising from immature cells that fail to develop normally during embryonic stages. Their origins diverge significantly: neuroblastoma stems from neural crest cells, which form parts of the nervous system, while nephroblastoma originates from undifferentiated kidney cells.
Regarding primary location, neuroblastoma frequently appears in the adrenal glands or other sites along the sympathetic nervous system, such as the neck, chest, or pelvis. Nephroblastoma, conversely, is almost exclusively found in the kidneys. The typical age of onset also shows a distinction; neuroblastoma often presents in younger infants, with a median age of diagnosis around 17 months, whereas nephroblastoma peaks in children aged three to four years.
Their growth patterns and spread also differ. Neuroblastoma has a higher tendency to be widespread at diagnosis, with cancer cells often spreading to bone marrow, bones, lymph nodes, liver, and skin. Neuroblastoma tumors can also encase or displace surrounding structures and blood vessels. Nephroblastoma, while also capable of metastasis, more commonly presents as a localized kidney mass and tends to spread to nearby lymph nodes, lungs, and liver.
Genetic factors contribute to both conditions. For neuroblastoma, inherited changes in the ALK and PHOX2B genes are associated with familial cases, though most neuroblastomas are not inherited. The MYCN oncogene, when amplified, is a sign that the neuroblastoma tumor may grow quickly. Nephroblastoma can be linked to specific genetic syndromes like WAGR syndrome, Denys-Drash syndrome, or Beckwith-Wiedemann syndrome, and mutations in genes like WT1, CTNNB1, and WTX are implicated in its development.
Diagnosis, Treatment, and Prognosis
Diagnosing both neuroblastoma and nephroblastoma involves a combination of imaging, laboratory tests, and biopsy. For neuroblastoma, imaging like ultrasound, CT, or MRI helps identify the tumor’s location and extent. Urine tests for elevated levels of catecholamine metabolites, such as vanillylmandelic acid (VMA) and homovanillic acid (HVA), are characteristic diagnostic markers for neuroblastoma. A biopsy confirms the diagnosis and helps classify the tumor histologically. For nephroblastoma, an abdominal ultrasound, followed by a CT or MRI scan, is performed to assess the kidney mass and check for spread.
Treatment approaches for these cancers vary depending on the specific type, stage, and biological features of the tumor, as well as the child’s age. Neuroblastoma treatment often involves a multi-modal approach, including surgery, chemotherapy, radiation therapy, and sometimes immunotherapy or high-dose chemotherapy with stem cell rescue, especially for high-risk cases. Some low-risk neuroblastomas in infants may even resolve without active treatment. For nephroblastoma, treatment commonly begins with several weeks of chemotherapy to shrink the tumor, followed by surgery to remove the tumor and the affected kidney. Post-surgery, additional chemotherapy or radiation therapy may be administered based on the tumor’s staging and histology.
The prognosis for both cancers has improved significantly with advancements in treatment. For neuroblastoma, the outlook is highly variable, influenced by age at diagnosis, tumor stage, and molecular features like MYCN amplification. Younger children, especially those under 18 months, generally have a better prognosis, with survival rates for low- and intermediate-risk cases often exceeding 90%. For nephroblastoma, the overall prognosis is favorable, with about 90% of treated children achieving a cure. Factors influencing nephroblastoma prognosis include tumor subtype and disease stage, with lower malignancy grades and less advanced stages correlating with better outcomes.