Ecchordosis Physaliphora Versus Chordoma

Case A: A clival/retroclival mass associated with bone destruction is evident on CT angiography images ( Figure 28-1 , A ). Prominent high signal intensity is noted on an axial T2 image. Heterogeneous T1 signal and diffuse enhancement is noted on sagittal T1 and T1 postcontrast images. Bone destruction, high T2 signal, and enhancement suggest the diagnosis of chordoma.

Case B: An osseous retroclival stalk/pedicle is evident on an axial CT image ( Figure 28-1 , B ). Axial and sagittal thin-section T2 images demonstrate an intradural, prepontine, cystic retroclival lesion attached to the dorsal clivus by the osseous stalk/pedicle without evidence of clival bony destruction. No enhancement is noted on the postcontrast fat-saturated T1-weighted image. A nonenhancing, cystic prepontine lesion attached to the clivus by an osseous stalk is the hallmark appearance of ecchordosis physaliphora (EP). The lack of diffusion-weighted imaging hyperintensity rules out an epidermoid cyst as a diagnostic consideration.

Case C: An osseous retroclival stalk/pedicle is evident on an axial CT images ( Figure 28-1 , C ). An axial thin-section T2 image demonstrates an intradural, prepontine, solid-appearing retroclival lesion attached to the dorsal clivus by the osseous stalk/pedicle without evidence of clival bony destruction. Diffuse contrast enhancement is present. The presence of enhancement excludes EP as a diagnostic consideration. The lack of bone destruction suggests the diagnosis of intradural/benign chordoma .