Blade of Grass Sign

An elongated, wedge- or V-shaped radiolucency extending over a long bone, which ends in a sharply demarcated curvilinear ‘margin’ at the diaphysis, seen in the advancing destructive phase of Paget’s disease of the bone
When involvement of the lytic phase is present in a long bone, the lytic changes may advance as a V- or wedge-shaped radiolucent area, clearly demarcated from the adjacent bone, likened to a blade of grass