Patients with long-standing Inflammatory Bowel Disease (IBD), particularly Ulcerative colitis and colonic Crohn's disease, are at increased risk of developing Colorectal dysplasia, a precursor to Colorectal cancer. Histologically, dysplasia in IBD is broadly categorised into conventional dysplasia and non-conventional dysplasia, each with distinct morphological characteristics and clinical implications.
Conventional dysplasia is the most common type encountered in IBD surveillance biopsies. It resembles the dysplasia seen in sporadic colorectal adenomas and is classified as low-grade or high-grade dysplasia based on architectural and cytological abnormalities. Histologic features include elongated hyperchromatic nuclei, loss of nuclear polarity, increased mitotic activity, glandular crowding, and epithelial stratification. Conventional dysplasia may present endoscopically as visible lesions or be detected incidentally on random biopsies during surveillance colonoscopy.
In contrast, non-conventional dysplasia encompasses several less common histological patterns that differ from the classical adenoma-like morphology. These include serrated dysplasia, hypermucinous dysplasia, crypt cell dysplasia, goblet cell–deficient dysplasia, and sessile serrated–like lesions. These variants may have subtle or atypical microscopic features, making them more difficult to recognise and potentially leading to underdiagnosis.
Recent studies have highlighted that certain forms of non-conventional dysplasia may carry a higher risk of progression to advanced neoplasia compared with conventional dysplasia. Therefore, accurate histological recognition is crucial for appropriate clinical management.
In clinical practice, detection of dysplasia typically prompts close surveillance, endoscopic resection of visible lesions, or surgical management in selected cases. Increasing use of advanced endoscopic techniques, such as chromoendoscopy, has improved the detection of dysplastic lesions in IBD patients undergoing surveillance.
Overall, awareness of both conventional and non-conventional dysplasia patterns is essential for pathologists and clinicians to ensure early detection and effective prevention of colorectal cancer in patients with IBD.