Differential diagnosis of pediatric solid renal mass

• Fetal lobulations of the kidney
• Dromedary hump
• Column of Bertin
• Acute pyelonephritis
• Mesoblastic nephroma
• Angiomyolipoma
• Wilms tumor
• Nephroblastomatosis
• Rhabdoid tumor
• Burkitt Lymphoma

Approach to the differential diagnosis of solid renal mass:

• US is the first step in imaging
• Be aware of congenital anomalies of renal formation
• In the clinical setting of infection, strongly consider the diagnosis of acute pyelonephritis. If this diagnosis is made, repeat the US in a month to ensure the “mass” has resolved
• In a neonate with a large mass, mesoblastic nephroma is most likely
• If the mass has fat, consider angiomyolipoma
• Otherwise you must move on to CT or MR and begin the workup for malignancy with a large mass, mesoblastic nephroma is most likely