Histopathological diagnosis of ulcerative colitis-associated neoplasia.

In patients with ulcerative colitis, tumor development occurs with an increase in the duration of the disease. Such lesions, known as ulcerative colitis-associated neoplasia (UCAN), histologically show a broad variety of findings such as low-grade dysplasia, high-grade dysplasia, and invasive carcinoma. For pathologists, however, the histopathological diagnosis of UCAN is occasionally difficult. Problems in pathological diagnosis can be summarized into the following three categories: (i) difficulty in discriminating UCAN from non-neoplastic inflammatory change; (ii) difficulty in discriminating UCAN from sporadic epithelial neoplasm; and (iii) difficulty in histological grading of UCAN. For most lesions, pathologists can make conclusive histological diagnoses without any problems. However, pathologists occasionally face diagnostic difficulties, especially in cases of lesions with borderline or indefinite histology and, therefore, at least two experienced gastrointestinal pathologists are needed to confirm the diagnosis. Hence, a confirmation is usually preferable for the estimation of tumor depth and lymphovascular invasion in digestive tract cancers as well as in UCAN. Immunohistochemistry for p53 and Ki-67 (MIB-1) is occasionally useful as an ancillary tool. Since UCAN has distinct characteristics compared to sporadic epithelial neoplasia, its treatment strategy should be carefully discussed by a multidisciplinary team, especially for cases of lesions with indefinite histology. At present, although surgical intervention such as total colectomy is the most promising procedure for UCAN, recent advances in endoscopic diagnosis and therapy are expected to improve future treatment strategy.