Sandbox: DDx Kidney mass

• Present at birth
• Haematuria

• Palpable abdominal mass

• Fetal hypercalcaemia

• Connective tissue growing between nephrons replacing most of the renal parenchyma
• Cellular clusters of spindle cells
• Mild nuclear pleomorphism
• Increased mitotic activity
• No blastema

• Antenatal U/S
• Well-defined mass with low-level homogeneous echoes
• Concentric echogenic and hypoechoic rings
• Increased vasculairty
• Polyhydramnios

• t(12;15)
• ETV6-NTRK3 gene fusion

Nonmalignant causes

anaplastic sarcoma clear cell sarcoma mesoblastic nephroma metanephric stromal tumor nephroblastomatosis / nephrogenic rests neuroblastoma oncocytoid carcinoma after neuroblastoma ossifying