ABSTRACT
Genetic alterations in a tubular adenoma with severe dysplasia arising in a Brooke ileostomy of a familial adenomatous polyposis patient were analyzed. Clinical and morphological characteristics suggest that ileal mucosa progressed to colonic metaplasia and then to dysplastic adenoma. Such changes at ileostomy sites are rare, and little is known about the associated genetic alterations. To determine whether metaplastic epithelium progression to adenoma in the ileum is subject to the same mutations identified in colon carcinogenesis, we evaluated somatic genetic alterations associated with sporadic colorectal cancer development. Sequences examined included mutation cluster regions of the p53 tumor suppressor gene and the k-ras oncogene. Using polymerase chain reaction and DNA sequencing, we identified a point mutation at codon 12 of the K-ras oncogene. To our knowledge, this is the first report of a ras mutation occurring in a tumor originating from ileal mucosa.
