Sandbox: DDx Kidney mass

• 1-2 yo patients
• Constitutional symptoms
• May have abdominal pain, constipation, proptosis, periorbital ecchymoses, back pain, weakness, hypertension, and subcutaneous nodules
• Opsoclonus myoclonus ataxia syndrome

• Heterogeneous mass on U/S
• Internal vascularity
• Necrosis
• Calcification

• Elevated levels of catecholamines, dopamine, homovanillic acid, and vanillylmandelic acid (VMA)

• Small round blue cells
• Thin pink fibrous septa
• Homer-Wright rosettes
• Neuropil-like stroma

• MYCN oncogene amplification
• PHOX2A gene mutation
• KIF1B gene mutation
• LMO1 gene mutation

Nonmalignant causes

anaplastic sarcoma clear cell sarcoma mesoblastic nephroma metanephric stromal tumor nephroblastomatosis / nephrogenic rests neuroblastoma oncocytoid carcinoma after neuroblastoma ossifying tumor renal cell carcinoma rhabdoid tumor translocation carcinoma (children)