Figure 1

Computed tomography and magnetic resonance imaging findings. Computed tomography (A, coronal view; B, transverse view) shows a large tumor starting at the level of the third sacrum (S3) and pushing the distal colon toward the right; its distal extension ends at the perineal mass. Magnetic resonance imaging (C, T1-weighted image, sagittal view; D, T2-weighted image, transverse view) shows isointensity relative to muscle on T1-weighted imaging and hyperintensity relative to muscle on T2-weighted imaging. The white arrows in each image indicate the tumor and its margin.