Claw sign (mass)

The claw sign is useful in determining that a mass arises from a solid structure rather than is located adjacent to it and distorts the outline.

It refers to the sharp angles on either side of the mass, which the surrounding normal parenchyma forms when the mass has arisen from the parenchyma. As such, normal parenchyma extends some way around the mass.

Examples where a claw sign is useful include:

• meningioma vs intra-axial brain tumor
• Wilms tumor vs neuroblastoma
• renal angiomyolipoma vs retroperitoneal liposarcoma