Sandbox: DDx Kidney mass

• 3-4 yo patients
• Asymptomatic abdominal mass
• May have abdominal pain, fever, nausea/vomiting, hematuria, and hypertension
• Beckwith-Wiedemann syndrome and WAGR syndrome

• Unilateral, smooth, firm, nontender, flank mass
• Does not cross the midline

• Elevated serum creatinine and BUN
• Reduced glomerular filtration rate
• Abnormal liver function tests
• Erythrocytosis, hypercalcemia, and acquired Von Willebrand disease

• Large heterogeneous solid mass on U/S
• Displace adjacent structures
• Lung and lymph nodes metastasis
• Renal vein thrombosis

• Triphasic pattern consisting of tubules, solid sheets of small round cells, and stroma
• Small round blue cells, nuclear pleomorphism, and irregular nuclear membrane

clustered glomerulus central (clear/white) space surrounded by a rim of intensely eosinophilic cytoplasm elongated and palisaded

• WT1 and WT2 genes on chromosome 11
• WTX gene on chromosome X

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) Wilms tumor of children