Contrast-enhanced computed tomography characterization of canine rectal neoplasms

Differential diagnosis of rectal neoplasms is necessary to determine an appropriate treatment plan. In humans, computed tomography (CT) is used to evaluate colorectal neoplasms. This retrospective study assessed the CT features of canine rectal neoplasms, including seventeen inflammatory polyps, six adenocarcinomas, three B-cell lymphomas and four leiomyomas on triple-phase CT. A mass lesion was observed in all seventeen cases of inflammatory polyps (100%), two of six adenocarcinomas (33%), and all four cases of leiomyoma (100%). Wall thickening was observed in four of six (67%) adenocarcinoma cases and all three (100%) lymphoma cases. The leiomyoma was more likely to show obstruction than inflammatory polyps, adenocarcinomas, and lymphomas. Homogeneous enhancement was detected in zero of seventeen (0%) inflammatory polyp cases, two of six (33%) adenocarcinoma cases, all three (100%) lymphoma cases, and all four (100%) leiomyoma cases in all post contrast phases. Lymphadenopathy was detected in three adenocarcinoma cases (50%) and three lymphoma cases (100%). Inflammatory polyps indicated a heterogeneous radial-enhancement mass. Leiomyomas indicated a homogeneous enhancement mass with bowel obstruction. In wall thickening lesions, adenocarcinoma indicated two-layer thickened annular lesions and lymphoma indicated homogeneous thickened annular lesions but less enhancement than the mucosa. These findings may help confirm the diagnosis and reduce the use of invasive biopsy procedures.