Claw sign (mass)

The claw sign is useful in determining whether a mass arises from a solid structure or 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. intraparenchymal brain tumour
• Wilms tumour vs. neuroblastoma
• renal angiomyolipoma vs. retroperitoneal liposarcoma