RESUMEN
Ulcerative colitis [UC] is a relapsing and remitting disease characterized by acute non-infectious inflammation and shallow ulceration with increased risk of carcinoma in long standing cases. This study was designed for application of new grading activity system. and assessement of Ki67 and P53 alterations in UC cases complicated with dysplasia. This study was performed on 99 colorectal endoscopic biopsy specimens. Sections stained with Haematoxyline and eosin were examined for the diagnostic criteria of UC. Immunohistochemistery staining for p53 and Ki67 done only for the dysplastic cases. The following lesions were diagnosed in the 99 collected cases:11 cases show chronic nonspecific colitis without fulfilling the criteria of diagnosis of ulcerative colitis.88 cases were diagnosed as ulcerative colitis and its related dysplasia, they include: 63 cases UC with no associated dyspiasia, 25 cases UC with dysplasia divided into: a] 12 cases as indefinite for dysplasia. b] 6 cases with low grade dysplasia, c] 3 cases with high grade dysplasia, and d] 4 cases lost during immunohistochemical preparation. UC grading system of activity should be applied in UC cases to evaluate the present activity and so the treatment, UC cases with dysplasia must have routine immunohistochemistery staining of both P53 and Ki67 to evaluate the type of dyspiasia especially indefinite for dyspiasia. Low grade dyspiasia show positive staining for both P53 and Ki 67 in lower two thirds of crypt epithelium, while high grade dyspiasia show positive staining for both P53 and Ki 67 in the whole crypt epithelium