NICE Classification of Colorectal Polyps

NICE is short for NBI (Narrow-band imaging) International Colorectal Endoscopic classification.

The basis of polyp classification using the NICE system is the texture and patterns that are observed on the surface of polyps through the use of narrow-band imaging (NBI). The classification uses staining, vascular patterns, and surface patterns to distinguish between hyperplastic and adenomatous colon polyps. Although it is linked to the Olympus company’s endoscopes, similar differential-diagnostic approaches have also been reported for devices manufactured by other companies. Clinically, the classification is used for small (less than 5 mm) or small (6 to 9 mm) polyps.

Narrow-band imaging uses short wavelengths of light (red-green-and-blue filters) to enhance the visualization of the colonic mucosa and vascular pattern of polyps and tumors. The short wavelengths of light penetrate the mucosa superficially. The blue filters enhance the appearance of capillaries, causing them to appear brown or black. The green filters penetrate deeper, and the contrast between the blood vessels and mucosa provides greater overall clarity of mucosal surface structures.

Polyps are classified as hyperplastic if they have the following characteristics:

• The blood vessels have a lighter or similar appearance to the surrounding tissue.
• The vascular network appears sparse and lacy, and the vessels small with no clear growth pattern.
• The surface of the polyps have circular patterns that appear in the form of white dots.

Growths are identified as adenoma if they have the following characteristics:

• The blood vessels have a darker appearance compared to the surrounding tissue.
• The network of vessels may appear lighter in the middle, with thicker and darker vessels surrounding it.
• White structures that correspond to the pits and the crypt openings of the epithelium may also be visible.
• The surface of the growth is oval and tubular.

Malignant growths are identified with the following characteristics:

• The blood vessels appear darker compared to the surrounding tissue, but may contain lighter patches.
• The vasculature pattern may have interruptions where vessels are absent.
• The surface does not have any distinct pattern.