Summary

Colorectal cancer (CRC) complicating ulcerative colitis (UC) accounts for about 1% of all cases of CRC. Such tumours develop from pre-existing foci of dysplasia in patients with extensive and long-standing UC. We report a case of UC-associated synchronous CRC and foci of high-grade dysplasia with an additional malignant focus in the appendix in a female patient after only 6 years of pancolitis who did not have other risk factors for the development of complications. The multiplicity and the timings of the early changes noted suggest that long-standing inflammation in UC randomly damages multiple genes in epithelial cells known to contribute to colorectal carcinogenesis. Current findings also support a molecular and pathological heterogeneity during multiclonal origin of synchronous tumours whereby differences occur at various sites that were absent during the initial stages of the disease.