What is the most common abdominal malignancy in children?

The most common abdominal malignancy in children is Wilms tumor, also known as nephroblastoma. This tumor specifically originates in the kidneys and predominantly affects children between the ages of 2 and 5. Due to its prevalence and the fact that it is primarily a kidney tumor, it is classified as the most common form of abdominal cancer in the pediatric population.

Neuroblastoma, while also common in children, primarily arises from neural crest cells and typically presents in the adrenal glands or along sympathetic nerve pathways, making it a notable but less prevalent abdominal malignancy compared to Wilms tumor. Hepatoblastoma, on the other hand, originates in the liver and, although it is a significant pediatric liver tumor, occurs less frequently than Wilms tumor. Rhabdomyosarcoma is a soft tissue sarcoma that can occur in various locations, including the abdomen, but it is not exclusive to the abdominal region and is less common than Wilms tumor overall.

Thus, understanding the epidemiology of these cancers helps clarify why Wilms tumor holds the designation of the most common abdominal malignancy in children.