Diagnosis of sessile serrated adenomas/polyps using endocytoscopy (with videos)

Sessile serrated adenomas/polyps (SSA/P) are considered to be precursors of colorectal cancers. They therefore need to be distinguished from hyperplastic polyps, and should be treated similarly to adenomas. Various endoscopic classifications for discriminating SSA/P have recently been proposed and validated, including the 'Type II-O' pit pattern in magnifying chromoendoscopy and the 'varicose microvascular vessel' in narrow-band imaging. However, there is currently no diagnostic consensus on the endoscopic appearance of SSA/P. Endocytoscopy (EC) is an emerging modality with diagnostic potential for SSA/P. EC is a type of a contact light microscopy, which allows in vivo visualization of cells and nuclei facilitating precise, real-time pathological prediction. SSA/P show oval gland lumens with small round nuclei in EC, indirectly reflecting the pathological features. EC has shown a sensitivity of 83.3% and a specificity of 97.8% for the diagnosis of SSA/P. EC is also a promising tool for the diagnosis of SSA/P with cytological dysplasia because of its ability to detect morphological changes in nuclei, which is the most important factor determining the presence of dysplasia in the lesion. However, clinical data validating the usefulness of EC are lacking, and further studies are required.