Which tumor is characterized by a nontender abdominal mass that may cross the midline in children?

Neuroblastoma is a common pediatric tumor that primarily arises from neural crest cells, often in the adrenal glands or sympathetic ganglia. One of its hallmark features is the presence of a nontender abdominal mass that can cross the midline, distinguishing it from other abdominal tumors in children. The mass is typically firm and can displace surrounding organs as it enlarges, leading to its characteristic presentation.

In neuroblastoma, the crossing of the midline often occurs because the tumor can grow in the retroperitoneal space. This is particularly important in diagnosis, as many other tumors like Wilms tumor tend to remain unilateral and are usually localized to one kidney. Recognizing the nontender nature of the mass is also critical, as it distinguishes neuroblastoma from some other tumors that might be associated with tenderness or signs of inflammation.

Understanding these characteristics is crucial for early diagnosis and appropriate management, as neuroblastoma can also present with systemic symptoms, depending on the stage and location of the disease.