Figure 12a.

Stage IIIB (cT3N2M0) squamous cell carcinoma of the anus. (a, b) Coronal CT images obtained at different levels show a locally extensive mass extending superiorly from the anorectal junction (arrows in a). Pathologic analysis demonstrated squamous cell carcinoma consistent with anal cancer, despite the relatively superior location. A prominent left internal iliac lymph node is also seen (arrow in b). (c, d) Coronal CT images obtained at different levels 3 months after completion of definitive chemoradiation therapy show a partial radiographic response of both the primary mass and the left internal iliac lymph node.