Histology: Sections show colonic mucosa including underlying muscularis mucosae. The biopsy is markedly abnormal, with surface ulceration, reduction in crypt density, areas of crypt destruction, and distortion of architecture. The lamina propria is densely expanded by chronic inflammatory cells, and this is accompanied by a diffuse neutrophilic infiltrate with cryptitis and the occasional crypt abscess. Granulomas are not readily apparent. The deep crypt epithelium shows prominent reactive nuclear hyperchromasia, but definitive cytomegalovirus viral effect is not seen. There is no evidence of dysplasia or malignancy. Immunohistochemistry for CMV is negative.
DIAGNOSIS: Sigmoid biopsy: Moderately severe active chronic colitis. Negative immunohistochemistry for CMV.