Final answer:
The most likely diagnosis for a 3-year-old patient presenting with a flank mass, hematuria, hypertension, and a mass that does not cross the midline is Wilms tumor.
Step-by-step explanation:
The most likely diagnosis for a 3-year-old patient presenting with a flank mass, hematuria, hypertension, and a mass that does not cross the midline is Wilms tumor, also known as nephroblastoma.
Wilms tumor is a type of kidney cancer that primarily affects children. It is the most common kidney cancer in children and is usually diagnosed between the ages of 3 and 4.
Treatment for Wilms tumor typically involves surgery to remove the tumor, followed by chemotherapy and sometimes radiation therapy.