What is the most common presentation of Wilms tumor?

The most common presentation of Wilms tumor, a type of kidney cancer primarily found in children, is indeed an abdominal mass. This tumor typically arises in one of the kidneys and can grow large enough to be palpable during a physical examination, often detected by a parent or physician when assessing for unrelated complaints or during routine check-ups. Due to its relatively fast growth rate, the abdominal mass can become prominent and visible even in the early stages of the disease.

While hematuria, flank pain, and enlarged lymph nodes can occur in patients with Wilms tumor, they are not as universally found in initial presentations as the abdominal mass is. Hematuria may be present in some cases, indicating bleeding within the tumor or kidneys, but it is not as common or prominent as the physical finding of an abdominal mass. Similarly, flank pain may arise as the tumor grows and exerts pressure on surrounding structures, but it is not a primary symptom. Enlarged lymph nodes can indicate spread of the disease but are typically discovered later in the course of illness or during staging evaluations. Therefore, recognizing the abdominal mass as the primary and most discernible manifestation is crucial for early diagnosis and intervention in Wilms tumor.