2.3 Images analysis
The laryngoscope images of vocal cord leukoplakia were independently
evaluated by two experienced laryngologists who were not informed of the
pathological diagnosis or other clinically relevant information. The two
laryngologists recorded the characteristics of vocal cord leukoplakia by
laryngoscopy, including size, thickness, texture, hyperemia, boundary,
and whether anterior commissure and bilateral vocal cords were involved.
Their consensus was used as the final diagnosis result. Such
characteristics were defined as follows: (1) size (unilateral vocal cord
leukoplakia covering more than half of the total area of the vocal cord
was defined as large leukoplakia; otherwise, the definition was small
leukoplakia); (2) thickness (leukoplakia was considered thick if
obviously exceeding the height of the vocal cord surface and the blood
vessels beneath the lesion were not visible; otherwise, it was
considered thin); (3) texture (leukoplakia with a rough and uneven
surface, which may manifest as papillary, verrucous, granular, or
scattered nodules was defined as irregular, whereas if the surface of
the lesion was flat and smooth, and the thickness of each part was
almost equal, it was judged to be regular); (4) hyperemia (mucosal
erythema or dilated blood vessels seen on or around the leukoplakia were
considered hyperemia); (5) boundary (if the boundary between the lesion
and the surrounding normal mucosa was clear, neat, and sharp, the lesion
boundary was considered clear, whereas if the boundary was disordered,
fuzzy, and rough, the lesion boundary was deemed unclear); (6) whether
anterior commissure was involved; (7) whether bilateral vocal cords were
involved; (8) the general classification of vocal cord leukoplakia under
a laryngoscope as proposed by Zhang et al. 5 The
groups in this classification system were as follows: (1) flat and
smooth type; (2) bulge and smooth type; and (3) bulge and rough type.