Dysplasia in Ulcerative Colitis
Dysplasia vs. Regenerative Atypia in Ulcerative Colitis (UC): The development of colorectal carcinoma in the setting of UC is preceded by dysplasia, usually in the flat atrophic portion of the mucosa. Dysplasia should be distinguished from reactive atypia in the regenerating mucosa, often seen in the areas of active inflammation. Dysplastic epithelium usually has dense eosinophilic cytoplasm in contrast to the bluish basophilic appearance of regenerating cells. The distinction between the two may be difficult and one should be careful while making a diagnosis of dysplasia in areas of active inflammation. This focus shows high-grade dysplasia in a raised lesion found during surveillance colonoscopy (visible dysplasia; adenoma-like DALM) in a patient with long-standing ulcerative colitis. There are complex distorted glands lined by pleomorphic cells with loss of polarity, irregular, enlarged, vesicular nuclei and prominent nucleoli. Mitotic activity is brisk. Notwithstanding the inflammation present, these cytologic and architectural features are sufficient for the diagnosis of high-grade dysplasia and not compatible with regenerative changes.