4 DISCUSSION
Vocal cord leukoplakia has the potential for malignant
transformation.7 Laryngoscopy is the main means to
diagnose vocal cord leukoplakia. The accurate diagnosis of the malignant
possibility of vocal cord leukoplakia is closely related to the clinical
experience of laryngologists. Previous research showed that the NBI
laryngoscopy could help to improve the diagnostic accuracy by observing
the morphology of microvessels on the mucosal
surface.8 However, since the NBI laryngoscopy has not
been fully popularized clinically, making accurate judgments also
require training.9 Most laryngologists still observe
vocal cord leukoplakia by WLI laryngoscopy. Therefore, it is of greater
clinical significance to improve the diagnostic accuracy of vocal cord
leukoplakia under WLI laryngoscopy.
Although the gross appearance of vocal cord leukoplakia with different
pathological properties is sometimes approximately similar, some
researchers have tried to use WLI laryngoscopy for the scoring and
classification of vocal cord leukoplakia to evaluate the possibility of
malignancy and guide treatment. Representative scoring systems are the
leukoplakia scoring system proposed by Fang et
al. 4 and the classification proposed by Zhanget al. 5 Fang et al. results showed that
age, lesion heterogeneity, and hyperemia were independent factors for
predicting malignant vocal cord leukoplakia. Afterward, the formula
(score = 0.060 × age + 2.609 × texture + 1.307 × hyperemia) was proposed
on the basis of the regression coefficient. This score is of some
clinical value for predicting the malignancy of vocal cord leukoplakia
(AUC = 0.86). Zhang et al. classified vocal cord leukoplakia into
three types according to roughness. Further studies by this team showed
that the classification of vocal cord leukoplakia into the low-risk and
high-risk groups had a certain auxiliary effect (AUC = 0.863) and helped
to guide the choice of clinical treatment.10,11 In
this classification system, type I mostly suggests low-risk leukoplakia,
whereas type III mainly suggests high-risk vocal cord leukoplakia.
However, the differential diagnosis of type II leukoplakia is not
accurate, mainly because this classification was only based on texture
and ignored other factors. Some studies have shown that under WLI
laryngoscopy, the existence of hyperemia12 and
vascular stippling13 are closely related to atypical
hyperplasia and malignancy. Although Fang’s scoring system considered
texture and hyperemia, it is not widely applied in clinical practice.
The main reason is that the formula of this scoring method is difficult
to remember, and in addition, there is also a lack of consideration of
other factors associated with malignant vocal cord leukoplakia (such as
color, size, and symmetry), which leads to an average diagnostic
efficiency (sensitivity 80.4%, specificity 81.5%).4
In order to improve the accuracy and objectivity of the evaluation of
the nature of vocal cord leukoplakia by laryngoscopy, all morphological
factors associated with benign and malignant leukoplakia were included
in this study by referring to the grading method of reflux finding score
(RFS) in the diagnosis of laryngopharyngeal reflux.14Scores were assigned according to the regression coefficient. The
regression analysis showed that hyperemia was the most important factor.
For easy memorization, 4 points were assigned to hyperemia, 2 points to
the involvement of anterior commissure and thickness, and 1 point was
assigned to size and texture. The final range of the score was 0–10
points. This scoring system showed a very strong consistency between the
two laryngologists (kappa = 0.809). The AUC of this LFS for the
diagnosis of benign and malignant vocal cord leukoplakia was 0.946,
which was higher than that of the Fang score (AUC=0.880) and Zhang
classification (AUC=0.742). The reference cutoff point for diagnosing
malignant vocal cord leukoplakia was ≥6 points. The sensitivity,
specificity, and accuracy of this scoring method were 93.8%, 83.6%,
and 86.0%, respectively. It can be seen from this study that hyperemia
of vocal cord leukoplakia is the most important predictor of malignancy
(it has a maximum weight of 4 points in the scoring system); thus, this
feature should be a focus of evaluation during laryngoscopy. This
characteristic of WLI laryngoscopy that corresponds to the performance
of NBI laryngoscopy is tortuous dilated microvessels, which is the main
observation point of NBI laryngoscopy used to judge the nature of the
lesions.15 To accurately judge whether vocal cord
leukoplakia is hyperemic, it is critical to observe as close as possible
to the vocal cord surface during laryngoscopy and pay attention to the
edge of the leukoplakia. In addition, the involvement of the anterior
commissure is closely related to the malignant transformation of vocal
cord leukoplakia (assignment of 2 points), which has not been reported
in other studies. It is necessary to report the relationship between
vocal cord leukoplakia and the anterior commissure to provide accurate
clinical information for subsequent minimally invasive surgical
treatment.