| [ Summary ] |
Dysplasia occurring in ulcerative colitis (UC) is a type of precancerous lesion requiring colectomy. Its recognition is particularly important because dysplasia is the only way of reliably predicting the risk of colitic cancer. The grading system proposed by Riddell andhis colleagues is widely accepted but interobserver variability is an issue to be overcome ; indeed, it was reported that κ values ranged from 0.29 to 0.58 when the lesions were divided into hyperplasia, regenerative change, low grade dysplasia, and high grade dysplasia. However, there is little difference in therapeutic strategies between low and high grade dysplasia, and the κ values were reported to be more than 0.61 when the lesions were divided into two categories determined by the presence or absence of dysplasia. The macroscopically visible lesions are designated as dysplasia-associated lesions or masses (DALMs) and often complicate invasive carcinomas, particularly in patients with DALMs found in the first endoscopy. Non-adenoma-like DALM usually shows an irregular protuberant or villous plaque with an ill-defined edge, and the gross appearance is distinct from sporadic-type adenoma in UC. One specific subtype of DALM is an adenoma-like lesion resembling sporadic adenoma. This paper also refers to the histological differentiations between these lesions. |