Sunday, April 29, 2012

How To Differentiate Neuroblastoma and Wilms Tumor

Renal masses are fairly common in the pediatric age group. Two of the most common are neuroblastoma and Wilms Tumor.

Neuroblastoma is a neuroendocrine tumor that usually develops in the adrenal glands, but can develop in any neuroectodermal tissue. One unique feature of disease is that a subset of children with metastatic disease located only in the liver, bone marrow, and skin, will demonstrate spontaneous regression. This Stage IV-S (S for special) does not require any form of chemotherapy.

Wilms tumor (also called nephroblastoma) is the most common renal malignancy in children. It develops from the embryologic metanephric blastema. The eponym was coined for German surgeon Max Wilms who first described the entity.

Since both tumors can be commonly found in the abdomen, they can easily be confused for each other radiographically. Here is a table that helps distinguish the two:

FeatureNeuroblastomaWilms Tumor
AgeLess than 2 yrsPeak at 3 yrs
Ca++Yes (stippled)No
Growth pattenSurrounds and engulfs vesselsDisplaces vessels
Effect on kidneyInferior displacement and rotationArises from kidney (claw sign)
Lung metsNoYes (20%)
Vascular invasionNoRenal vein, IVC, right atrium

Adapted from Pediatric Imaging: The Fundamentals, 1e by Lane Donnelly. 

Wilms Tumor with Claw Sign
Wilms Tumor with Claw Sign
Source: Radiopaedia

To summarize, Wilms tumor occurs in slightly older children, is centered in the kidney, and has vascular spread. Neuroblastoma is typically younger and more agressive, metastasizing by direct spread to liver and bone.

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