Review Question - QID 210394

A 3-year-old boy is brought in by his parents for a well-visit. The child can run, make short sentences, and stack 6 cubes. He eats a varied diet and lives at home with his brother. The patient has no significant medical history and was born to a G2P2 mother at 35 weeks gestation. His parents are concerned that he has gained weight recently but otherwise are content with his development. His temperature is 98.8°F (37.1°C), blood pressure is 99/68 mmHg, pulse is 120/min, respirations are 14/min, and oxygen saturation is 99% on room air. Physical exam demonstrates an active young boy who is agreeable. Cardiac and pulmonary exam are within normal limits. Abdominal exam demonstrates a palpable mass limited to the right side of the abdomen. Neurological exam reveals stable gait and 5/5 strength in the upper and lower extremities. A CT scan is performed as seen in Figure A. Which of the following is the most appropriate description of this patient's presentation?