Cytologic and histologic changes in irradiated loops of transplanted small bowel.

The histopathologic and cytopathologic changes in irradiated transplanted loops of bowel were assessed in 10 dogs. Five received conventional radiotherapy (CRT), and five received hyperfractionated doses of radiotherapy (HFRT) over the same period. Both groups exhibited identical cytologic findings, including blunting of villi and significant crypt atypia that could be mistaken for malignancy. Histologic examination corroborated the cytologic findings. At the end of the experiment two of the dogs that received CRT had developed strictures. One showed extensive submucosal fibrosis, while the other showed submucosal atrophy.