An 18-month-old male presents to the emergency department wi…

An 18-month-old male presents to the emergency department with a clinical history of intermittent, colicky abdominal pain, vomiting, and a palpable “sausage-shaped” mass in the right upper quadrant. During the sonographic evaluation, a 3.2 cm multi-layered, ovoid mass is identified. In the transverse plane, the mass demonstrates concentric rings of alternating echogenicity, while the sagittal plane displays a “pseudokidney” appearance. What is the most likely diagnosis and location?