Missed ascending colon cancer in an older patient with extensive ulcerative colitis.

To cite: Tominaga K, Saida Y, Takahashi K, et al. BMJ Case Rep Published online: [please include Day Month Year] doi:10.1136/ bcr-2014-203783 DESCRIPTION A man in his early 70s with a 15-year history of extensive ulcerative colitis (UC) was referred for surveillance ileocolonoscopy (SI). He had no highrisk factors for UC-associated colorectal cancer (CRC) except for the extent of active mucosal inflammation. Two years ago, he had undergone an SI with surveillance biopsy of the entire colorectum with no dysplasia or CRC detected. He had no surveillance the previous year despite a recommendation for annual SI. An ascending colon cancer was detected in the subsequent ileocolonoscopy (figure 1). There was no colorectal dysplasia, but biopsy revealed active mucosal inflammation throughout the colorectum including the peritumoural area. Proctocolectomy was performed and resected specimens revealed a moderately differentiated adenocarcinoma with subserosal invasion (figure 2). No histopathological characteristics of UC-associated CRC were detected. There was no synchronous dysplasia or CRC, and no metastasis. The patient remains alive without recurrence or metastasis 7 years after the proctocolectomy. In contrast to sporadic microsatellite-stable CRC, UC-associated CRC is characterised by a relatively young age of onset, synchronous CRC and less frequent occurrence of right-sided tumours. In this case, although the cancer existed within an area of active mucosal inflammation, it was indistinguishable from a sporadic cancer due to the absence of the characteristic features of UC-associated CRC. Compared with older patients with non-inflammatory bowel disease, it has been reported that missed colorectal cancers among older patients with UC are less likely to occur in the right-sided colon. This case supports the use of meticulous SI, including for cancers in the right-sided colon, in older patients.