Table 2. The classifications of laryngeal lesions.

Classification	Lesion manifestations
Ni Classification [2011]	I: IPCLs are almost invisible, while oblique and arborescent vessels of small diameter can be seen
	II: IPCLs are almost invisible, but the vessels that can be seen have a larger diameter
	III: the mucosa is white and the IPCLs are invisible, and whether oblique and tree-like-vessels can be seen is dependent on the thickness of the white patch
	IV: mucosal IPCLs are arranged comparatively regularly and are low in density. There are bifurcations or slight dilations of the capillary terminals, and IPCLs appear to be scattered, tiny, dark brown spots. Oblique and arborescent vessels are usually invisible
	Va: with their high density and prominent dilation, IPCLs can appear solid or hollow, brownish, speckled, and shaped in various ways
	Vb: as IPCL destructs, its remnants look like snakes, earthworms, tadpoles, or branches. Additionally, the micro-vessels dilate, elongate, and appear woven
	Vc: necrotic tissue covers the lesion surface, and the tumor surface is irregularly covered with IPCLs which appear as brownish speckles or tortuous shapes with uneven density
Ni Classification of the vocal cord leukoplakia [2019]	I: in contrast to IPCLs, white plague is observed, with obliquely running vessels and branching vessels under it
	II: white patches appear, but IPCLs, obliquely running vessels, or branches cannot be seen
	III: on the surface of the vocal cord mucosa without leukoplakia, IPCLs appear as small brown spots with a relatively regular arrangement without boundaries. There are no obliquely running or branching vessels
	IV: IPCLs can be observed, showing large brown spots and embedded at the surface of white plaques
	V: IPCLs can be seen, shown as large brown spots, which appear at the surface of the vocal cord mucosa outside the leukoplakia with obvious boundaries
	VI: IPCLs are visible, characterized by large brown spots or twisted earthworm-like vessels distributed at the surface of the leukoplakia and also at the surface of the vocal cord epithelium outside the leukoplakia
ELS Classification [2016]	Benign lesions: longitudinal vascular changes
	Premalignant lesions: perpendicular vascular changes
Puxeddu Classification [2015]	0 (normal mucosa): thin-end regular subepithelial vessels connecting with a thicker and deeper arborescent vascular network running parallel to the epithelium
	I (inflammation): the subepithelial vessels are increased in number and size, with irregular and sometimes crossing directions.
	II (hyperplasia):
	(i) Initial stage: intra-CLs are visible running toward the surface. CLs are generally still very thin and short, arising from the underlying inflammatory vasculature, with a scattered distribution;
	(ii) Mature hyperplasia: the deeper inflammatory vascular network is not visible, and only the elongated CLs can be easily seen;
	(iii) Vegetating keratosis: the deeper inflammatory vascular network is often not visible, and the elongated CLs are difficult to see. A particular type of “bobby-pin” which is encased by typical papilloma can be seen in laryngeal papillomatosis.
	III (mild-moderate dysplasia): vascular changes become more consistent, with elongated small vessels in the typical “bobby-pin” shape, but some arborescence appears at the end of the CLs
	IV (high-grade dysplasia/carcinoma in situ/invasive carcinoma): the vascularity of the chorion is more evident, and CLs appear significantly dilated, with various shapes and a wide range of vascular architectural changes such as corkscrews or tree-like patterns

IPCLs, intrapapillary capillary loops; CLs, capillary loops.